1. Obli-Gator
  2. Oblique Angel
  3. Obscene Jester
  4. Obsolete Techie
  5. Obtuse Angler
  6. OctoBear
  7. Octopuss in Boots
  8. Offense Attorney
  9. Ogre Achiever
  10. Old Town Rogue
  11. Olfactory Worker
  12. Olympic Mentalist
  13. Omniscient Ignoramus
  14. Omnomnomnivore
  15. On-and-off Guard
  16. One-And-A-Halfling
  17. One-and-a-Halfling
  18. One-Armed Archer
  19. One-Armed Bandit
  20. One-Eyed Beholder
  21. One-hit Wanderer
  22. One-Hit Wonder
  23. One-Legged Centipede
  24. Onion Ringleader
  25. Onomatopoet
  26. Open Sorceror
  27. Operetta Phantom
  28. Optical Illusionist
  29. Optimus Slime
  30. Orc Angel
  31. Orc Bishop
  32. Orc de Triomphe
  33. Orc of the Covenant
  34. Orc-in-the-Road
  35. Organ Grinder
  36. Origami Dragon
  37. Original Impostor
  38. ORLY Owl
  39. Orthodontisaur
  40. Oscillating Fanboy
  41. Ottoman Umpire
  42. Out-of-Commissioner
  43. Out-of-Frame Monster
  44. Out-of-Service Dog
  45. Out-of-Shapeshifter
  46. Out-of-Tuna
  47. Out-Sorcerer
  48. Outsourced Monster
  49. Oval Lord
  50. Over-Confident Noob
  51. Over-Seasoned Warrior
  52. Overbearing Waiter
  53. Overconfident Noob
  54. Oxy-Moron
  55. Ozone Slayer