Thomas Dunbar (18 August 1868 - 28 April 1908) was a Scottish association footballer who played for Celtic and Rangers. He is one of only two players to cross the Old Firm divide twice, the other being Kenny Miller.
Dunbar initially signed for Celtic from Busby Cartvale in 1890 and his debut came at Rangers during a 2-1 league victory on 2 May 1891. A few months later, in November 1891, he joined Rangers but returned to Celtic by July the following year. He played another five years with Celtic and left the club in 1897 having made a total of sixty appearances for the club across both spells.