Where the Sullivan name comes from

Sullivan came out of Irish, an anglicised form of O Suilleabhain (Ó Súilleabháin). The Irish original passed into English as O'Sullivan, and Sullivan is that same name with the O' clipped away. Sullivant survives alongside it as an alternative form of the surname.

Emigration out of Ireland carried the name a long way from where it started, and it is now most common in North America. It is also found in Australia and in Britain. In the 2010 United States census, Sullivan ranked as the 105th most common surname.