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. Omniscient Ignoramus
  13. Omnomnomnivore
  14. On-and-off Guard
  15. One-And-A-Halfling
  16. One-and-a-Halfling
  17. One-Armed Archer
  18. One-Armed Bandit
  19. One-Eyed Beholder
  20. One-hit Wanderer
  21. One-Hit Wonder
  22. One-Legged Centipede
  23. Onion Ringleader
  24. Onomatopoet
  25. Open Sorceror
  26. Operetta Phantom
  27. Optical Illusionist
  28. Optimus Slime
  29. Orc Angel
  30. Orc Bishop
  31. Orc de Triomphe
  32. Orc of the Covenant
  33. Orc-in-the-Road
  34. Organ Grinder
  35. Origami Dragon
  36. Original Impostor
  37. ORLY Owl
  38. Orthodontisaur
  39. Oscillating Fanboy
  40. Ottoman Umpire
  41. Out-of-Commissioner
  42. Out-of-Frame Monster
  43. Out-of-Service Dog
  44. Out-of-Shapeshifter
  45. Out-of-Tuna
  46. Out-Sorcerer
  47. Outsourced Monster
  48. Oval Lord
  49. Over-Confident Noob
  50. Over-Seasoned Warrior
  51. Overbearing Waiter
  52. Overconfident Noob
  53. Oxy-Moron
  54. Ozone Slayer