Magrs was born in Jarrow, Tyne and Wear on 12 November 1969. In 1975, he moved with his family to Newton Aycliffe, County Durham; his parents divorced shortly after the move. At the age of 17, Magrs was queer-bashed, and his father was the police officer who took the report on the incident; it was the last time Paul Magrs saw his father.

In Newton Aycliffe, Magrs attended Woodham Comprehensive School, where Mark Gatiss was two years ahead of him and in the same drama group. Magrs went on to Lancaster University, where he received a first class BA in English (1991), an MA in Creative Writing (1991) and a PhD in English (1995). His doctoral thesis was on Angela Carter regarded as a Queer writer.

Magrs is the author of numerous fiction and non-fiction works. His first published writing was the short story "Patient Iris", published 1995 in New Writing Four (edited by A. S. Byatt and Alan Hollinghurst). This was soon followed by his debut novel, Marked for Life, the same year. Magrs' first three novels, Marked for Life, Does It Show? (1997) and Could It Be Magic? (1998), share characters, a magical realist tone and a setting: the fictional Phoenix Court council estate in Newton Aycliffe.

Magrs' first children's book, Strange Boy (2002), prompted controversy due to homosexual content involving its 10-year-old protagonist and a 14-year-old neighbour. Representatives of the NASUWT teachers' union and the conservative Christian Institute argued that the book should not be stocked in school libraries, and some newspapers suggested that doing so in England would be illegal due to the Section 28 ban on "promoting homosexuality" in schools. However, the Chartered Institute of Library and Information Professionals supported libraries' purchase of Strange Boy, as did representatives of Stonewall and other gay rights organizations. Magrs noted that the book was "about 95% autobiographical" and described the controversy as "ludicrous".

Magrs' other novels include Aisles (2003) and To the Devil ... a Diva! (2004); he has also published several short stories. His novel Exchange was shortlisted for the 2006 Booktrust Teenage Prize and was longlisted for the 2007 Carnegie Medal.

Magrs has written several novels, short stories and audio dramas relating to Doctor Who, many of which also feature his character Iris Wildthyme. Iris is generally portrayed as an eccentric and unreliable Time Lady, whose TARDIS takes the form of a London Routemaster double-decker bus (the No. 22 to Putney Common). Iris Wildthyme was originally created for Magrs' unpublished first novel, which was named after her; another version of Iris also appears in Marked for Life. The character features in all of Magrs' four contributions to BBC Books' Eighth Doctor Adventures, in several Big Finish Productions audio dramas by Magrs and other writers, and in short story and novella collections published by Big Finish and Obverse Books. Magrs has also written licensed Doctor Who fiction without Wildthyme, including the 2007 novel Sick Building (which made the shortlist for the Doncaster Book Award) and the audio series Hornets' Nest, which marked the first time Tom Baker had returned to play the Doctor in a full-length drama since he left the role in 1981.

Magrs' current novel series is The Adventures of Brenda and Effie, starring Brenda, the Bride of Frankenstein, who has now retired and runs a B&B in Whitby. She and her friend Effie, a local white witch, investigate spooky goings on in the town. , there have been four books in the series; a fifth, The Bride That Time Forgot, is due for publication in October. The fourth book, Hell's Belles, features characters from Magrs' early Phoenix Court books.

Magrs is Senior Lecturer in English Literature and Creative Writing at Manchester Metropolitan University, where he began work in 2004, having formerly taught at the University of East Anglia. With Julia Bell, Magrs edited several issues of the University of East Anglia's literary journal Pretext and The Creative Writing Coursebook (2001).

Novels

• Marked for Life (1995)
• Does it Show? (1997)
• Could It be Magic? (1998)
• Modern Love (2000)
• All the Rage (2001)
• Strange Boy (2002)
• Hands Up! (American title, The Good, the Bat and the Ugly) (2003)
• Aisles (2003)
• To the Devil — A Diva! (2004)
• Exchange (2006)
• Twin Freaks (2007)
• The Diary of a Dr Who Addict (2010)

The Adventures of Brenda and Effie

• Never the Bride (2006)
• Something Borrowed (2007)
• Conjugal Rites (2008)
• Hell's Belles (2009)
• The Bride That Time Forgot (2010)

Short story collections

• Playing Out (1997)
• Twelve Stories (Salt Publishing, 2009)

Other works

• "Never the Bride" (1998 BBC Radio 4; expanded version 2008, BBC7)
• "Life After Mars" (2002 BBC Radio 4) part of the Fictional Familiars series.
• "Sunseeker" (2005 BBC Radio 4)
• "The Foster Parents" (2007, in Comma Press' short story collection Phobic)
• "The Longsight Branch" (2 July 2008 BBC Radio 4 Afternoon Reading)
• "The Dreadful Flap" (2009, in Obverse Books' short story collection Iris Wildthyme and the Celestial Omnibus)
• "The Delightful Bag" (2009, in Obverse Books' short story collection The Panda Book of Horror)

Doctor Who novels for BBC Books

• The Scarlet Empress (1998, featuring the Eighth Doctor, Sam Jones and Iris Wildthyme)
• The Blue Angel (1999, featuring the Eighth Doctor, Fitz Kreiner, Compassion and Iris Wildthyme; written with Jeremy Hoad)
• Verdigris (2000, featuring the Third Doctor, Jo Grant and Iris Wildthyme)
• Mad Dogs and Englishmen (2002, featuring the Eighth Doctor, Fitz Kreiner, Anji Kapoor and Iris Wildthyme)
• Sick Building (2007, featuring the Tenth Doctor and Martha Jones)

Doctor Who plays for Big Finish

• The Stones of Venice (2001, featuring the Eighth Doctor and Charley Pollard)
• Excelis Dawns (2002, featuring the Fifth Doctor and Iris Wildthyme)
• The Wormery (2003, featuring the Sixth Doctor and Iris Wildthyme; written with Stephen Cole)
• Horror of Glam Rock (2007, featuring the Eighth Doctor and Lucie Miller)
• The Wishing Beast & The Vanity Box (2007, featuring the Sixth Doctor and Melanie Bush)
• The Zygon Who Fell to Earth (2008, featuring the Eighth Doctor and Lucie Miller)
• The Boy That Time Forgot (2008, featuring the Fifth Doctor and Nyssa)
• The Companion Chronicles - Ringpullworld (2009, featuring the Fifth Doctor and Turlough)
• The Companion Chronicles - Find and Replace (2010, featuring the Third Doctor, Jo Grant and Iris Wildthyme)

Doctor Who plays for BBC Audio

• Hornets' Nest 1: The Stuff Of Nightmares (Fourth Doctor, Mike Yates)
• Hornets' Nest 2: The Doll Of Death (Fourth Doctor, Mike Yates)
• Hornets' Nest 3: The Circus Of Doom (Fourth Doctor, Mike Yates)
• Hornets' Nest 4: A Sting In The Tale (Fourth Doctor, Mike Yates)
• Hornets' Nest 5: Hive Of Horror (Fourth Doctor, Mike Yates)
• Demon Quest 1: The Relics Of Time (Fourth Doctor)
• Demon Quest 2: The Demon Of Paris (Fourth Doctor)
• Demon Quest 3: A Shard Of Ice (Fourth Doctor)
• Demon Quest 4: Starfall (Fourth Doctor)
• Demon Quest 5: Sepulchre (Fourth Doctor)

Doctor Who short stories

• "Femme Fatale" in More Short Trips (1999)
• "The Longest Story in the World" in Short Trips and Side Steps (2000)
• "Jealous, Possessive" in Zodiac (2002)
• "Kept Safe and Sound" in Companions (2003)
• "Euterpe" in The Muses (2003)
• "Lust" in Seven Deadly Sins (2005)
• "The Wickerwork Man" in Farewells (2006)
• "Fanboys" in Snapshots (2007)
• "Zombie Motel" in Doctor Who Storybook 2008 (published 2007)
• "Hello Children, Everywhere" in Doctor Who Storybook 2009 (published 2008)

Other plays for Big Finish

• Wildthyme at Large (2005, Iris Wildthyme)
• Land of Wonder (2009, Iris Wildthyme)

Books as editor

• Wildthyme on Top (2005, Iris Wildthyme, Big Finish)
• Iris Wildthyme and the Celestial Omnibus (2009, Iris Wildthyme, Obverse Books, edited with Stuart Douglas)
• The Panda Book of Horror (2009, Iris Wildthyme, Obverse Books, edited with Stuart Douglas)