Gamp - Martin Chuzzlewit

Harcourt is a messenger to the king in Henry IV, Part 2.

Imp Y Celyn - Soul Music - Terry Pratchett

Joe Bagstock - Dombey & Son

Kylara - Dragonriders of Pern - Anne McCaffrey

Lady Bertram - Mansfield Park

Margaret (Meg) March - Little Women - Lousia May Alcott

Nick Culpeper, from Rewards and Fairies by Rudyard Kipling

Owl from the Winnie the Pooh books by A.A. Milne.

Panthino is a servant of Antonio in "The Two Gentlemen of Verona".

Questular Rontok - Hitchhikers Guide To The Galaxy

Rosita Francetti, in Frying as Usual by Joan Lingard

Sara Carew from A Little Princess by Frances Hodgeson-Burnett.

Tangled Mane in White Horses and Black Bulls by Allan C. Jennings

Ursula - Much Ado About Nothing - William Shakespeare

Vincent Crummles - Nicholas Nickleby

Willoughby (historical) is a supporter of Bolingbroke In Richard II

Xanthe from Greek mythology, one of the daughters of Oceanus

Yentl from the play of the same name by Leah Napolin.

Zoraida - plus it's literal meaning, as well as who this is.

Perhaps means "enchanting woman" in Arabic, but possibly a name invented by Cervantes for a character in his novel "Don Quixote" (1606),

in which Zoraida is a beautiful Moorish woman of Algiers who converts to Christianity & elopes with a Spanish officer.

Abraham Slender - The Merry Wives of Windsor

Ben Gunn from Treasure Island by Robert Louis Stephenson.

Cadwal (real name Arviragus) is the second son of the king in Cymbeline, stolen away in infancy by Morgan, and brought up as Morgan's child.

Duck Man - Discworld - Terry Pratchett

Edgar is the worthy, legitimate son of Gloucester in King Lear. He disguises himself as "Poor Tom".