| Name | Book/story/stage title | Notes
|
| Oakes, Dr | | Doctor for Wrykyn College
|
| Oakes, Elliott | Death at the Excelsior | Detective with Paul Snyder's Detective Agency
|
| Oakes, Mrs | The Gold Bat | Dr Oakes' wife at Wrykyn
|
| Oakley, Jane | | A very wealthy woman
|
| Oakshott | Jeeves Takes Charge | Butler to Bertie Wooster' uncle Willoughby
|
| Oakshott | | Lady Julia Ukridge's butler
|
| Oakshott, Bill | Uncle Dynamite | A young man
|
| Oates, Eustace | | Policeman in Totleigh-in-the-Wold
|
| O'Brien, Isaac | | Business name of Izzy Previn, bookmaker & boxing promoter
|
| O'Connell | The Luck Stone | A ruffian at Alderton College
|
| O'Hara, Donough | | Boy at Wrykyn College
|
| Oldest Member, The | | A golfer and story teller
|
| 'Old Nick' | French Leave | A penniless French Marquis
|
| Oliphant, Jane | Portrait of a Disciplinarian | Recently engaged to Frederick Mulliner
|
| Opal, Senator Ambrose | Hot Water | A leading 'dry' senator
|
| Opal, Jane | Hot Water | His daughter
|
| Osbaldistone, Miss | Jane Gets Off the Fairway | A manly young woman
|
| O'Toole, Maggie | Piccadilly Jim | Real name of Celestine, a maid
|
| O'Toole, Sergeant | Mr McGee's Big Day | A New York policeman
|
| Otto of Saxe-Pfennig, Prince | | Head of the invading German army
|
| 'Otto the Sausage' | Misunderstood | A member of the Frith Street gang
|
| Otway | The Gold bat | Boy at Wrykyn College
|
| Outwood, Mr | | House master at Sedleigh College
|
| Ovens, G. | | Proprietor of the Emsworth Arms
|
| Ovide | French Leave | A clerk
|
| Owoki, General | The Military Invasion of America | Head of invading Japanese army
|
