Eleazer Kingsbury Foster (May 20, 1813 – June 13, 1877) was a lawyer and politician in the United States.
His father Eleazer Foster was a prominent lawyer of New Haven until his early death in 1819.
In 1854 he was appointed State's Attorney for New Haven County, and was nominated Register in Bankruptcy when that office was created, and continued in both these positions till his death.
Besides his professional success, Foster's social qualities gained him the warm regard of a large circle of friends.
He married Mary, daughter of William C. Codrington, a lady of English birth, and formerly of Kingston, Jamaica, but then of New Haven, Jan 2, 1838.