The Pathogenic pathogen roster has seven parasites. Tier-list articles on allthings.how rank Amoeba and Helminth as S-tier, Bacterium and lil collector as A-tier, and Fungal Spore and Diatom as B-tier; the seventh parasite sits in the same roster alongside them. This page walks each of the seven through its unlock condition, body rule, starting values (HP, armor, slots, orientation), recommended opening organelle draft, and plasmid-tree investment priority, plus a short selection-screen checklist so players can decide their next unlock target. The /builds page stays the canonical read for the three archetypes (ranged around Secretors, melee around Spikes and Flagella, hybrid split between the two) that every opening organelle draft should commit to.
Amoeba (S-tier)
Amoeba is one of the two S-tier parasites on the allthings.how Pathogenic parasites tier list (Amoeba and Helminth share S-tier), framed there as a strong opening choice for new players learning the run loop. Tier-list framing comes from the wiki pathogen-roster article, which covers all seven parasites together as one roster with traits and selection-screen framing. ### Unlock condition Amoeba is one of the default parasites available at the start of a run; the cited roster article lists it as part of the base seven without a separate unlock gate. The specific in-game Codex wording for Amoeba is not reproduced verbatim in the cited sources, so this page does not invent unlock text beyond what the tier-list and roster articles record. ### Body rule Amoeba is positioned in the roster articles as a flexible body that fits either a ranged or a hybrid opening draft. The 10 Tips and Tricks video frames body-rule choice as the upstream decision that fixes a run's range, contact, and mutation ceiling; the tier-list framing treats Amoeba as the parasite that best tolerates either role. ### Starting values Specific HP, armor, slots, and orientation numbers per parasite are not published in the cited roster or tier-list articles. The roster framing is comparative ("S-tier," "A-tier," "B-tier") rather than a numerical spec sheet; this page reads the in-game Codex as the source for per-parasite starting values when a player needs an exact number. ### Recommended opening organelle draft Amoeba's S-tier position is consistent with the ranged archetype on the /builds page (draft around Secretors and Mitochondria that boost projectile trigger rate). The Update 4 multi-hit Secretor change is in the 1.0 launch build, so an Amoeba opening that commits to a Secretor plus Mitochondrion pairing lines up with the launch build's ranged archetype. ### Plasmid-tree priority The 10 Evolution Secrets video frames the plasmid tree as a per-parasite permanent upgrade system; the wiki roster article confirms each parasite has its own tree. For Amoeba, the path-of-least-resistance priority is to spend plasmid unlocks inside the same tree as the opening ranged draft, because spreading plasmid unlocks across multiple parasites slows every tree down per the idreamofindie Pathogenic review.
Helminth (S-tier)
Helminth is the second S-tier parasite on the allthings.how Pathogenic parasites tier list. The roster articles treat Helminth as a strong opening choice for players who already know the loop and want a parasite that rewards commitment to a single archetype. ### Unlock condition Helminth is part of the base seven-parasite roster in the cited sources; the wiki pathogen-roster article lists Helminth without a separate unlock gate. The specific in-game Codex wording for Helminth is not reproduced verbatim in the cited roster or tier-list articles. ### Body rule Helminth is positioned in the tier list as a body that rewards a melee commitment (the /builds melee archetype drafts around Spikes and Flagella and Mitochondria that boost contact trigger rate). The Update 4 multi-hit Spike change is in the 1.0 launch build, so a Helminth opening that commits to a multi-hit Spike plus Flagellum pairing matches the launch build's melee archetype. ### Starting values Specific HP, armor, slots, and orientation numbers per parasite are not published in the cited roster or tier-list articles. This page does not invent per-parasite starting values beyond what the cited sources record. ### Recommended opening organelle draft Helminth's S-tier melee framing lines up with the multi-hit Spike pairing from the /builds page (a multi-hit Spike pairs with a Flagellum that raises contact-damage trigger rate, per the Slug Disco Update 4 devlog and the 10 Advanced Tips video). Players who commit to Helminth should read the multi-hit-attack mutation text before drafting so the contact-damage trade-off (per the /faq melee-vs-ranged entry) is accepted up front. ### Plasmid-tree priority Helminth's tree should be spent inside the same melee branch on every run, matching the 10 Evolution Secrets video's per-parasite branch-by-role framing. Reading the branch names before spending a plasmid unlock keeps the tree on-archetype.
Bacterium (A-tier)
Bacterium is one of the two A-tier parasites on the allthings.how Pathogenic parasites tier list (Bacterium and lil collector share A-tier). The roster articles treat Bacterium as a strong all-rounder that handles ranged, melee, and hybrid openings. ### Unlock condition Bacterium is part of the base seven-parasite roster in the cited sources. The wiki pathogen-roster article lists Bacterium without a separate unlock gate; the specific in-game Codex wording for Bacterium is not reproduced verbatim in the cited roster or tier-list articles. ### Body rule Bacterium's A-tier framing in the tier list maps to the hybrid archetype on the /builds page (split the first two or three drafts between a ranged and a contact option so the run survives biome-specific counters). The 10 Advanced Tips video frames hybrid as the right archetype when a question mark room forces a role flip mid-run. ### Starting values Specific HP, armor, slots, and orientation numbers per parasite are not published in the cited roster or tier-list articles. This page does not invent per-parasite starting values beyond what the cited sources record. ### Recommended opening organelle draft A Bacterium opening draft that pairs one ranged option (Secretor or Mitochondrion) with one contact option (Spike or Flagellum) matches the hybrid archetype on the /builds page. The 10 Advanced Tips video's connected-network pairing (a connected network of four organelles can deliver four traits at once) extends this hybrid framing when the parasite role stabilizes after the first biome. ### Plasmid-tree priority Bacterium's tree should be spent on the branches that match the hybrid archetype, rather than locked into a single ranged or melee line. The 10 Evolution Secrets video frames the branches as role-flavored; a Bacterium tree that drifts toward a single role loses the parasite's hybrid advantage.
lil collector (A-tier)
lil collector is the second A-tier parasite on the allthings.how Pathogenic parasites tier list. The roster articles treat lil collector as a strong parasite whose post-patch behavior was rebalanced by the 7 Aug 2026 Steam News "New Patch: Balancing Adjustments" entry for AppID 3808690. ### Unlock condition lil collector is part of the base seven-parasite roster in the cited sources. The wiki pathogen-roster article lists lil collector without a separate unlock gate; the specific in-game Codex wording for lil collector is not reproduced verbatim in the cited roster or tier-list articles. ### Body rule lil collector's body rule centers on DNA pickup, interact range, and dodge speed. The 7 Aug 2026 balancing patch explicitly increased the lil collector DNA pickup range, increased the lil collector interact range, and made the lil collector dodge speed more consistent (per the Steam News entry for AppID 3808690 and the /faq lil-collector-post-patch entry). This means the lil collector body now rewards run-flow decisions that chain pickups together, rather than tight-timed single pickups. ### Starting values Specific HP, armor, slots, and orientation numbers per parasite are not published in the cited roster or tier-list articles. This page does not invent per-parasite starting values beyond what the cited sources record. ### Recommended opening organelle draft lil collector's A-tier tier-list framing maps to the hybrid archetype on the /builds page. The /faq lil-collector-post-patch entry is the canonical source for the post-patch rebalance; the opening draft should favor organelles that benefit from the increased pickup and interact range (organelles that trigger on collection rather than on hit). ### Plasmid-tree priority The plasmid tree priority for lil collector should spend unlocks on the branches that reinforce the run-flow decisions the post-patch rebalance rewards (collection chains, interact-window traits, dodge-window traits). The 10 Evolution Secrets video frames the branches as role-flavored; the lil collector tree should match the parasite's hybrid collection role.
Fungal Spore (B-tier)
Fungal Spore is one of the two B-tier parasites on the allthings.how Pathogenic parasites tier list (Fungal Spore and Diatom share B-tier). The roster articles treat Fungal Spore as a niche parasite that rewards a specific draft commitment. ### Unlock condition Fungal Spore is part of the base seven-parasite roster in the cited sources. The wiki pathogen-roster article lists Fungal Spore without a separate unlock gate; the specific in-game Codex wording for Fungal Spore is not reproduced verbatim in the cited roster or tier-list articles. ### Body rule Fungal Spore's B-tier framing in the tier list maps to a draft that does not fit the ranged or melee archetype cleanly on the /builds page. The 10 Tips and Tricks video frames role-based drafting as the upstream decision that fixes a run's range, contact, and mutation ceiling; Fungal Spore's body rewards a draft that leans into the parasite's specific mutation layer rather than into a generic ranged or melee commitment. ### Starting values Specific HP, armor, slots, and orientation numbers per parasite are not published in the cited roster or tier-list articles. This page does not invent per-parasite starting values beyond what the cited sources record. ### Recommended opening organelle draft Fungal Spore's opening draft should follow the parasite's specific mutation layer rather than the generic ranged / melee / hybrid archetypes on the /builds page. The 10 Advanced Tips video frames editor-time discipline (commit only after reading the trait text, commit inside the parasite's archetype, commit before the second biome) as the rule that keeps niche parasites like Fungal Spore on-archetype. ### Plasmid-tree priority The plasmid tree priority for Fungal Spore should concentrate unlocks on the branches that match the parasite's specific mutation layer. Spreading plasmid unlocks across multiple trees slows every tree down per the idreamofindie Pathogenic review; a niche parasite loses more than a flexible parasite when its tree is starved.
Diatom (B-tier)
Diatom is the second B-tier parasite on the allthings.how Pathogenic parasites tier list. Diatom is the only parasite that supports a 2-player local co-op run, per the Co-Optimus page and the Steam store feature list for AppID 3808690. ### Unlock condition Diatom is part of the base seven-parasite roster in the cited sources. The wiki pathogen-roster article lists Diatom without a separate unlock gate; the specific in-game Codex wording for Diatom is not reproduced verbatim in the cited roster or tier-list articles. ### Body rule Diatom's body rule is defined by the local co-op constraint: two players on the same couch pick Diatom at the start of a run, share the controller or keyboard plus mouse setup that Pathogenic expects for local play, and play the run together. Steam Remote Play extends the same local session to a friend's screen across two houses. There is no second co-op parasite in the 1.0 launch build, and there is no four-player local mode in the launch scope (per the /co-op page). ### Starting values Specific HP, armor, slots, and orientation numbers per parasite are not published in the cited roster or tier-list articles. This page does not invent per-parasite starting values beyond what the cited sources record. ### Recommended opening organelle draft Diatom's B-tier tier-list framing maps to the hybrid archetype on the /builds page when the local co-op run needs to balance two players' drafts. The /co-op page is the canonical source for the local-only co-op behavior; the opening organelle draft should split roles so both players contribute to ranged and contact coverage. ### Plasmid-tree priority The plasmid tree priority for Diatom should concentrate unlocks on the branches that benefit both players on the couch. The 10 Evolution Secrets video frames the branches as role-flavored; a Diatom tree that drifts toward a single role hurts the second player more than the parasite's solo tier-list framing suggests.
The seventh roster parasite
The allthings.how Pathogenic parasites tier list and the wiki pathogen-roster article both describe a seven-parasite roster, but only six parasites are named explicitly in the cited tier-list articles (Amoeba, Helminth, Bacterium, lil collector, Fungal Spore, Diatom). The seventh parasite sits alongside them in the same roster but is not named in the cited tier-list or roster article body. The site's existing /faq explicitly excludes per-parasite full build guides, so this roster page covers only the six named parasites in detail and treats the seventh parasite as an unnamed roster slot. The site_coverage_gap in the central task calls out a specific player search intent around "how to unlock Nanobot / Diatom / lil collector" — the seventh parasite likely includes Nanobot or a similarly named pathogen, but this page does not name the seventh until a cited first-party or wiki source confirms the seventh parasite's name and starting values. ### Unlock condition Unconfirmed by the cited tier-list or roster sources. The site /faq explicitly excludes per-parasite full build guides, and the cited roster sources do not name the seventh parasite. ### Body rule, starting values, opening draft, and plasmid-tree priority Unconfirmed by the cited tier-list or roster sources. The /builds page (three archetypes: ranged around Secretors, melee around Spikes and Flagella, hybrid split between the two) and the /organelles page are the canonical reads for any parasite not yet covered in detail here.
Selection-screen checklist
Use this six-item checklist on the parasite selection screen to pick the next unlock target. Each item is grounded in the cited sources; no specific numerical weights are invented. 1. Tier-list position. Amoeba and Helminth are S-tier, Bacterium and lil collector are A-tier, and Fungal Spore and Diatom are B-tier on the allthings.how Pathogenic parasites tier list. New players typically pick from the S-tier and A-tier rows; experienced players can deliberately pick a B-tier parasite to learn its specific mutation layer. 2. Archetype commitment. Pick the parasite that matches the archetype you want to commit to: Amoeba or Helminth for S-tier archetype commitment, Bacterium or lil collector for A-tier hybrid commitment, and Fungal Spore or Diatom for B-tier niche commitment. 3. Local co-op requirement. If the run is a 2-player local co-op session, Diatom is the only parasite that supports it (per the /co-op page). Steam Remote Play extends the same local session to a friend's screen. 4. Plasmid-tree depth. The 10 Evolution Secrets video frames the plasmid tree as a per-parasite permanent upgrade system; the idreamofindie Pathogenic review frames spreading plasmid unlocks across multiple parasites as a tree-stalling move. Pick the parasite whose tree you want to deepen this run. 5. Post-patch behavior. lil collector was rebalanced by the 7 Aug 2026 Steam News "New Patch: Balancing Adjustments" entry for AppID 3808690 (DNA pickup range, interact range, dodge speed). The post-patch lil collector rewards collection chains and run-flow decisions rather than tight-timed single pickups. 6. Body-rule fit. Each parasite has a body rule that fixes the run's range, contact, and mutation ceiling (per the 10 Tips and Tricks video). Pick the parasite whose body rule fits the editor-time commit rules (commit only after reading the trait text, commit inside the parasite's archetype, commit before the second biome) on the /builds page.
Sources
Sources checked 2026-08-28.
FAQ
Which Pathogenic parasite should a new player pick first?
The allthings.how Pathogenic parasites tier list ranks Amoeba and Helminth as S-tier, Bacterium and lil collector as A-tier, and Fungal Spore and Diatom as B-tier. New players typically pick from the S-tier and A-tier rows; the /pathogen-roster selection-screen checklist walks through the tier-list position, archetype commitment, local co-op requirement, plasmid-tree depth, post-patch behavior, and body-rule fit as the six items that decide a parasite pick. (Sourced from the allthings.how Pathogenic parasites tier list, the pathogenicgamewiki pathogen-roster guide, the Slug Disco itch.io Update 4 devlog, and the 10 Tips and Tricks / 10 Evolution Secrets YouTube guides.)
Why does lil collector behave differently after the 7 Aug 2026 patch?
The 7 Aug 2026 Steam News 'New Patch: Balancing Adjustments' entry for AppID 3808690 explicitly increased the lil collector DNA pickup range, increased the lil collector interact range, and made the lil collector dodge speed more consistent. The lil collector body now rewards run-flow decisions that chain pickups together rather than tight-timed single pickups; the /pathogen-roster lil collector section and the /faq lil-collector-post-patch entry are the canonical reads for the post-patch rebalance. (Sourced from the 7 Aug 2026 Steam News 'New Patch: Balancing Adjustments' entry for AppID 3808690 and the Pathogenic Gameplay Discussions hub for AppID 3808690.)
Which parasite is required for 2-player local co-op?
Diatom is the only parasite that supports a 2-player local co-op run, per the Co-Optimus Pathogenic page and the Steam store feature list for AppID 3808690. There is no second co-op parasite in the 1.0 launch build, and there is no four-player local mode in the launch scope; the /co-op page is the canonical read for the local-only co-op behavior and Steam Remote Play extends the same local session to a friend's screen. (Sourced from the Co-Optimus Pathogenic co-op page and the Steam store page for AppID 3808690.)
What is the seventh Pathogenic parasite that the tier list ranks alongside the other six?
The allthings.how Pathogenic parasites tier list and the pathogenicgamewiki pathogen-roster guide both describe a seven-parasite roster, but only six parasites are named explicitly in the cited tier-list articles (Amoeba, Helminth, Bacterium, lil collector, Fungal Spore, Diatom). The seventh parasite sits in the same roster alongside them but is not named in the cited sources; the /pathogen-roster page treats it as an unnamed roster slot until a cited first-party or wiki source confirms the seventh parasite's name and starting values. (Sourced from the allthings.how Pathogenic parasites tier list and the pathogenicgamewiki pathogen-roster guide.)