O (2)

• Tristes Tropiques (1) Ordeal (Sentinel) by Martha
• Origin Story (Spider-Man/Incredibles) by JJonahJameson
• Orturmoriwen (Buffy/Tolkien) by Twinkledru J
• The Other Side of the Sky (Doctor Who/Sandman) by Aces
• Library (1) Our Unconquerable Soul (Sentinel/Poltergeist the Legacy) by Sealie
• Ourselves and Immortality (Doctor Who) by LizBee
• Out Of Time (Harry Potter/Doctor Who) by Dacian Goddess
  Severus Snape and Hermione Granger begin an interesting association. How well can they make it last when neither of them is exactly as they seem?
• Out of the Dark (Doctor Who) by AstroGirl
  Jenny finds the limits of the universe, and keeps right on going.
• Road To Shalka (5) Out of the Dark (Doctor Who) by Soldeed
  Jasmine is gone. But with a new companion at his side and the Master at his back, the Doctor may yet have the chance of a happy ending.
• Out of the Valley (Stargate) by Sandman
• Outgeniused (or: How to Get Fired From the Apple Store in Three Easy Steps) (Doctor Who) by Casira
  Kate Stowe's seen a lot of strange problems come up at the Genius Bar, but this one qualifies as the strangest she's seen yet... Presenting a bit of shameless insanity, featuring the Doctor, a race of aliens with quite inconvenient taste, and several unorthodox ways to break your iPod's warranty. (In other words: crackfic ahead!)
• An Outrageous Amount of Running (Doctor Who) by Gnossienne Nr1
  It's Monday. It's raining. It's three days till Christmas, Donna's new boss is an idiot and nothing exciting will ever happen to her again. Not that anything exciting ever happened to her in the first place. Your basic JE-fixit.
• Outside These Walls (Sentinel) by Jael Lyn
• Outside the Hourglass (Torchwood) by Aeshna
  "Does this sort of thing happen a lot?" Spoilers for TW2.05, Adam
• Overheard (Sentinel) by DCStreets
• Overheard in the ICU (Stargate/House) by Kalquessa
• Ozymandias in Hell (Doctor Who) by PonyGirl
  Martha learns about a side of the Doctor she hasn't seen before. Well, make that nine sides, actually.