Series with the first letter - "O"
- O sabor das margaridas (2018–2020)
- Oban Star-Racers (2006)
- Obi-Wan Kenobi (2022–…)
- Occupied (2015–…)
- Ocean Girl (1994–1997)
- October Faction (2020)
- October Road (2007–2008)
- Oddballs (2022–…)
- Oddities (2010–…)
- Odio Il Natale (2022–…)
- Odissea (1968–…)
- Odwilz (2022–…)
- Odysseus (2013–…)
- Off the Map (2011)
- Office Girls (2011–…)
- Oggy and the Cockroaches: Next Generation (2022–…)
- Oh Doctor Beeching! (1995–1997)
- Oh Hell (2022–…)
- Oh! My Lady (2010–…)
- Okupas (2000)
- Olive Kitteridge (2014–…)
- Oliver Beene (2003–2004)
- Olympus (2015–…)
- Omnibus (1967–2003)
- On Becoming a God in Central Florida (2019–…)
- On Location (1976–…)
- On My Block (2018–…)
- On Pointe (2020–…)
- On the Job (2021)
- On the Spectrum (2018)