Ō (letter o with macron) may refer to:

• Ō (Latin script), a letter in many languages using the Latin script
• O with macron (Cyrillic), in many languages using the Cyrillic alphabet
• Ō (Japanese surname)

See also

• Ō clan, a historical Japanese clan

This disambiguation page lists articles associated with the title Ō.
If an internal link led you here, you may wish to change the link to point directly to the intended article.