Worm

A worm was any manner of creature that tended to be round, long, and articulated.

Serpentine (higher) lifeforms
 * Deathworms (TV: Doctor Who)
 * Prisoner Zero (TV: The Eleventh Hour)
 * Psychic Worms (AUDIO: The Wormery)
 * The Process (PROSE: Cat's Cradle: Time's Crucible)
 * Voracious Craws (PROSE: Sick Building)
 * Wurms (PROSE: The Art of Destruction)
 * Harmonelids (COMIC: Earworm)
 * Alvarian space wyrms (COMIC: The Forgotten)

Lower lifeforms
 * Earthworms
 * Oroborous Worms (PROSE: The Mary-Sue Extrusion)
 * Jakra worms (PROSE: Ghosts of India)
 * Spulver Worms (PROSE: Coldheart)
 * Bore worms (PROSE: The Undertaker's Gift)
 * Alien tapeworms (PROSE: Slow Decay)
 * Myxilinic frost-worm (PROSE: The Colour of Darkness)
 * Thermortian Sand Worm (COMIC: The Forgotten)
 * Alifabe (COMIC: Sky Scraper)
 * Natrium Worm (COMIC: The Salt Solution)
 * Alvega Earthworm (COMIC: The Amaryll Challenge)
 * Norebo Worm (PROSE: Nightdreamers)
 * Bookworms (COMIC: Hunger from the Ends of Time)

Other creatures mistaken for worms:
 * Giant maggot (TV: The Green Death)
 * Cybermat (TV: Revenge of the Cybermen)
 * Horda (TV: The Face of Evil)
 * Fendahl (TV: Image of the Fendahl)

Other uses:
 * Donna Noble compared Time Lords to worms after witnessing the severed hand of the Tenth Doctor grow into a new Doctor. (TV: Journey's End)
 * Wormholes are unrelated except by name.