Sullivan is an Irish surname, from the Gaelic O Suilleabhain, meaning "descendant of Suilleabhan", a byname usually explained as "dark-eyed" or "little dark eye". It is one of the most common surnames in Ireland and has become a first name with the friendly short form Sully. Sullivan has been in the US top 1000 since 2002, climbed from number 455 in 2015 to 314 in 2025 and is at its best rank yet.