Worm

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

Serpentine (higher) lifeforms
 * Deathworms (DW: Doctor Who)
 * Prisoner Zero (DW: The Eleventh Hour)
 * Psychic Worms (BFA: The Wormery)
 * The Process (NA: Cat's Cradle: Time's Crucible)
 * Voracious Craws (NSA: Sick Building)
 * Wurms (NSA: The Art of Destruction)
 * Harmonelids (DWA: Earworm)
 * Alvarian space wyrms (IDW: The Forgotten)

Lower lifeforms
 * Earthworms
 * Oroborous Worms (BNA: The Mary-Sue Extrusion)
 * Jakra worms (NSA: Ghosts of India)
 * Spulver Worms (EDA: Coldheart)
 * Bore worms (TWN: The Undertaker's Gift)
 * Alien tapeworms (TWN: Slow Decay)
 * Myxilinic frost-worm (TDL: The Colour of Darkness)
 * Thermortian Sand Worm (IDW: The Forgotten)
 * Alifabe (DWA: Sky Scraper)
 * Natrium Worm (DWA: The Salt Solution)
 * Alvega Earthworm (TV21: The Amaryll Challenge)
 * Norebo Worm (TN: Nightdreamers)
 * Bookworms (IHP: Hunger from the Ends of Time)

Other creatures mistaken for worms:
 * Giant maggot (DW: The Green Death)
 * Cybermat (DW: Revenge of the Cybermen)
 * Horda (DW: The Face of Evil)
 * Fendahl (DW: 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. (DW: Journey's End)
 * Wormholes are unrelated except by name.