List of parasitic organisms

''This is a list of organisms that are true parasites upon other organisms. For more information on this topic, see main article:'' Parasitism. For information on parasitoids, see main article: Parasitoid.

Endoparasites
(endo = within; parasites that live inside their hosts)

Plants

 * Rafflesia

Arthropoda

 * Acarapis woodi
 * Sacculina

Helminths

 * Acanthocephala
 * Ascariasis (roundworms)
 * Cestoda (tapeworms) including: Taenia saginata (human beef tapeworm), Taenia solium (human pork tapeworm), Diphyllobothrium latum (fish tapeworm) and Echinococcosis (hydatid tapeworm)
 * Clonorchis sinensis (the Chinese liver fluke)
 * Dracunculiasis (Guinea Worm Disease)
 * Enterobius vermicularis (pinworm)
 * Filariasis
 * Hookworm
 * Loa loa
 * Onchocerciasis (river blindness)
 * Schistosomiasis
 * Strongyloides stercoralis
 * Toxocara canis (dog roundworm)
 * Trichinella
 * Whipworm

Fungi

 * Ringworm
 * Gymnosporangium and other rusts
 * Pyrenophora teres
 * Cordyceps

Protists (Protozoa)

 * Balantidium coli (the only ciliated protozoan to infect humans)
 * Giardia lamblia (the most common intestinal protozoan in the United States)
 * Trichomonas vaginalis
 * Naegleria fowleri (facultative parasite causing amoebic meningitis)
 * Entamoeba histolytica (causes Amebiasis, common in developing countries)
 * Kinetoplastid protists of the Trypanosoma and Leishmania genera (sleeping sickness, Chagas disease and leishmania)
 * Apicomplexan parasites including "Plasmodium" (malaria), "Toxoplasma" (toxoplasmosis), and "Cryptosporidia" (cryptosporidiosis)

Fictional endoparasites

 * Black Oil
 * Facehuggers, the parasite laying stage in the lifecycle of xenomorphs
 * The Flood, from the video game Halo
 * Goa'uld, from the TV series Stargate SG-1
 * Las Plagas, from the video game Resident Evil 4.
 * Lavos
 * Metroids (and X Parasites from the Metroid Fusion video game)
 * Killer parasitic worms from Slither.
 * Trill (Star Trek)
 * Yeerks
 * Kraata
 * Bone Leechs from Blood 2.
 * Bulbmin from Pikmin 2.
 * G.U.I.L.T. from Trauma Center: Under the Knife.
 * The Wirrn, from the BBC series Doctor Who.

Ectoparasites
(ecto = outside; parasites that live on but not within their hosts, for example, attached to their skin)

Plants

 * Broomrape
 * Cuscuta
 * Mistletoe
 * Santalum, hemi-parasitic. (Sandalwoods and Quandongs)
 * Toothwort
 * The wood rose, Dactylanthus taylorii

Arthropoda

 * Acarina (Ticks, some mites)
 * Cymothoa exigua
 * many Hippoboscoidea (Tsetse Flies, Sheep Keds, and relatives)
 * Oestridae (bot flies)
 * Phthiraptera (Lice)
 * Siphonaptera (Fleas)
 * Tantulocarida

Annelids

 * Hirudinea (some leeches)

Vertebrates

 * Candiru (Vampire fish of Brazil, really a facultative parasite)

Fictional ectoparasites

 * Brain slugs from Futurama.
 * Headcrabs from the Half-Life series or similar brainsuckers from X-COM: Apocalypse, though these species can be considered parasitoids rather than parasites.
 * The Flood from Halo. They come in three different forms: Infection Form, Combat Form, and Carrier Form.
 * Krana from the LEGO Bionicle series.
 * Nopal from the Jack Vance story Nopalgarth, also called The Brains of Earth.
 * Puppet Masters from Robert A. Heinlein's 1951 novel The Puppet Masters.
 * Shovel-Creatures, which prey on free thought from The Hitchhiker's Guide to the Galaxy movie.
 * Venom from the Marvel Comics Universe.