O (1)

• Object Impermanence (Doctor Who) by PonyGirl
• Odd Man Out (Champions) by The Blue Librarian
• Ode to a Sentinel on the Anniversary of the Encroachment of a Freeloading Anthropologist (Sentinel) by Carolyn Claire
• Of Doctors and Watchers (Buffy/Doctor Who) by Krab Apple
• Underground Holidays (1) Of Holly and Hobgoblins (Labyrinth) by Wai-Jing Waraugh
  Though surrounded by family, Sarah feels lonely at Christmas. There is a present she has not even admitted to herself that she wants. Only one person can give it to her, but will he, and she, realize her wish in time? And can she give something in return?
• Of Shadows and Demons (1) Of Shadows and Demons (Sentinel/Buffy) by Mackie
• Of Tiny White Vans and Time Machines (Doctor Who/No 1 Ladies Detective Agency) by Emmyangua
  Once a month the Doctor visits a small garage in Gaborone, Botswana where the best mechanic in Botswana (and in the Doctor's eyes, the whole universe) helps keep the TARDIS going that little bit longer.
• Break (2) Of Two Worlds (Star Trek: Reboot) by Yahtzee
  Spock has the opportunity to choose between the Prime universe and his own.
• Future Winnings (4) Oil on Wood (X-Files/Star Trek: Voyager) by Ecolea
• Road To Shalka (2) Old Friends (Doctor Who) by Soldeed
  Jasmine is starting to have second thoughts about setting off across the universe with this strange new Doctor. But she'll soon have other things on her mind.
• Old Friends Make the Worst Enemies (Buffy/Doctor Who) by Sahiya
• Old Things Made New (Doctor Who) by Carmen Sandiego
  The Doctor doesn't regenerate, Rose does.
• Omega Is Not Equal To One (The Future Is Now Remix) (Doctor Who) by AstroGirl
• Omphalos (Star Trek: Deep Space Nine/Buffy) by Marcus Rowland
• On Earth As in Heaven (Harry Potter) by Duniazade
  Two wanderers ask for hospitality. But gifts from the gods are sometimes strange.
• On the Other Side of Hate (Harry Potter) by Lin Lawless
  Severus has spent three years making Hermione's life as difficult as possible, in hopes that she'll resign her post and leave Hogwarts. When she does, however, he discovers that it's not in his best interest if she leaves, after all.
• In Time And Destiny (7) On the Threshold (Sentinel) by Becky
• Once Out of Nature (3) Once Out of Nature (Highlander) by Selena
  The Immortals have a new group of deadly enemies: scientific researchers intent on learning their secrets. Now it's Cassandra's turn to ask Methos for help, as she risks her identity and both their lives.
• Once Upon a Time (Highlander/Doctor Who) by Franavu
  Methos tells a story.
• Once Upon a Time (Doctor Who) by TangledWood
• One (Earth) Day in the Lives of the Doctor and Romana (Doctor Who) by LizBee
• One Feather (Labyrinth) by Xaviere Jade
  Here's the day Sarah thought would never come. Sarah gets a message and a gift. Then her whole life changes forever.
• One of These Mornings (Doctor Who) by Branwyn
• Only A Dream (Sentinel) by BethB
• Countess and the Doctor (3) Only Biography (Vorkosiverse/Doctor Who) by Sahiya
  Biographies were the Doctor's favorite literary form.