| Work | Description | Characters |
|---|---|---|
| Ol' Man Adam an' His Chillun | collection of folk tales | 1 |
| Omashu | episode of Avatar: The Last Airbender (S1 E3) | 1 |
| Omoi, Omoware, Furi, Furare | Japanese manga | 1 |
| Omori | 2020 horror role-playing video game | 1 |
| Once Burned | Book by Peter David, from 1998 | 3 |
| Once Upon a Planet | Short story | 6 |
| Once Upon a Time | American television series | 2 |
| Once Upon a Time in Hollywood | 2021 novel by Quentin Tarantino | 1 |
| Once Upon a Time in Hollywood | 2019 film directed by Quentin Tarantino | 1 |
| Once Upon a Time... Man | French animated TV series | 2 |
| One Flew Over the Cuckoo's Nest | novel by Ken Kesey | 1 |
| One Flew Over the Cuckoo's Nest | 1975 drama film based on the novel by Ken Kesey | 1 |
| One Foot in the Grave | British TV Comedy Series | 1 |
| One Hundred and One Dalmatians | 1961 American animated adventure film produced by Walt Disney | 1 |
| One Piece | Japanese manga series | 11 |
| One Piece | Japanese media franchise | 26 |
| One Piece | Japanese anime television series | 23 |
| One Piece: Stampede | 2019 Japanese anime film | 1 |
| One-Punch Man | Japanese anime television series | 2 |
| One-Punch Man | Japanese manga series by Yūsuke Murata | 2 |
| One-Punch Man | media franchise | 19 |
| One-Punch Man | Japanese manga series by One | 1 |
| One Shot | book by Lee Child | 1 |
| One Thousand and One Nights | collection of west asian stories and folk tales compiled in Arabic | 2 |
| One, Two, Buckle My Shoe | book | 1 |
| On Her Majesty's Secret Service | 1969 James Bond film by Peter R. Hunt | 1 |
| Only Fools and Horses | British television sitcom | 1 |
| On With the New | 1938 film by Dave Fleischer | 1 |
| Open Secrets | Book by Dayton Ward, from 2009 | 1 |
| Operation – Annihilate! | episode of Star Trek: The Original Series (S1 E29) | 6 |
| Orange Is the New Black | American comedy-drama series | 3 |
| Orgoglio e Pregiudizio | 1957 television series | 7 |
| Orgullo y Prejuicio | 1966 television miniseries | 6 |
| Original Sin | Star Trek novel by David R. George III | 1 |
| Orion's Hounds | Book by Christopher L. Bennett, from 2005 | 9 |
| Orlando furioso | opera by Antonio Vivaldi (1727) | 1 |
| Orlando Furioso | epic poem by Ludovico Ariosto | 1 |
| Orlando Innamorato | book by Matteo Maria Boiardo | 1 |
| Orphan's Benefit | 1934 Mickey Mouse short by Burt Gillett | 1 |
| Os Dez Mandamentos | telenovela | 1 |
| Oshi no Ko | Japanese manga series | 1 |
| Oshi no Ko | Japanese anime television series | 1 |
| Otello | opera by Giuseppe Verdi | 1 |
| Othello | play by Shakespeare | 3 |
| Ouran High School Host Club | 2011 TV Drama | 4 |
| Ouran High School Host Club | Japanese anime television series | 1 |
| Ouran High School Host Club | 2006 shōjo manga series directed by Takuya Igarashi | 2 |
| Our Flag Means Death | 2022 American television series | 1 |
| Our Man Bashir | episode of Star Trek: Deep Space Nine (S4 E10) | 8 |
| Our Mrs. Reynolds | episode of Firefly (S1 E6) | 1 |
| Outbound Flight | book | 1 |
| Out of Gas | episode of Firefly (S1 E8) | 2 |
| Out of Sight | 1996 novel by Elmore Leonard | 1 |
| Out of Sight | 1998 film by Steven Soderbergh | 1 |
| Out of the Inkwell | 1938 film by Dave Fleischer | 1 |
| Out of the Past | episode of The Legend of Korra (S1 E9) | 1 |
| Over a Torrent Sea | Star Trek novel | 5 |
| Overlord | Japanese light novel series | 1 |
| Overwatch | 2016 multiplayer first-person shooter video game | 18 |
| Overwatch | video game series | 4 |
| Overwatch | digital comics series | 4 |
| Overwatch 2 | upcoming video game developed by Blizzard Entertainment | 5 |
| Overwatch animated media | 3 | |
| Ozark | American drama series | 1 |
| Pain | 2007 video game | 1 |
| Parade of the Wooden Soldiers | 1933 film by Dave Fleischer | 1 |
| Paradise Lost | epic poem by John Milton (1667) | 2 |
| Paradiso | third part of Dante's Divine Comedy | 1 |
| Paranormasight: The Seven Mysteries of Honjo | 2023 video game | 1 |
| Parasyte | Japanese manga series and its franchise | 3 |
| Parks and Recreation | American comedy television series | 17 |
| Part One: Master and Apprentice | episode of Ahsoka | 1 |
| Part Three: Time to Fly | episode of Ahsoka | 1 |
| Part Two: Toil and Trouble | episode of Ahsoka | 1 |
| Party Central | 2013 film" | 2 |
| Past Imperfect | quest in Star Trek Online | 1 |
| Past Tense | 1 | |
| Past Tense, Part I | episode of Star Trek: Deep Space Nine (S3 E11) | 5 |
| Past Tense, Part II | episode of Star Trek: Deep Space Nine (S3 E12) | 4 |
| Patata | Wikimedia disambiguation page | 1 |
| Pathways | Book by Jeri Taylor, from 1998 | 8 |
| Paul, Apostle of Christ | 2018 film directed by Andrew Hyatt | 1 |
| Paul et Virginie | novel by Jacques-Henri Bernardin de Saint-Pierre | 1 |
| Paul of Dune | 2008 novel by Brian Herbert and Kevin J. Anderson | 1 |
| Pawns and Symbols | book by Majliss Larson | 4 |
| Peaky Blinders | British period drama television series (2013–2022) | 3 |
| Peanuts | comic strip by Charles M. Schulz | 4 |
| Peep Show | television series | 5 |
| Penguins of Madagascar | 2014 computer-animated film directed by Eric Darnell and Simon J. Smith | 1 |
| Penny Dreadful | 2014 British-American horror drama television series | 1 |
| Penumbra | episode of Star Trek: Deep Space Nine (S7 E17) | 1 |
| People Just Do Nothing | television series | 6 |
| People of Earth | episode of television series Star Trek: Discovery | 1 |
| Pep Comics | comic book | 1 |
| Perchance To Dream | Book by Howard Weinstein, from 1991 | 5 |
| Percy Jackson film series | film series from 2010, adaptation, American children's fantasy adventure | 2 |
| Percy Jackson & the Olympians | children's fantasy adventure series | 3 |
| Père Goriot | 1835 novel by Honoré de Balzac | 1 |
| Perfect Cherry Blossom | video game | 3 |
| Peril at End House | book | 1 |