Ernst Henrik Estlander (18 September 1870, Helsinki – 5 February 1949) was a Finnish legal scholar, professor at the University of Helsinki and politician. He was a member of the Diet of Finland from 1897 to 1906 and of the Parliament of Finland from 1907 to 1913 and again from 1916 to 1945, representing the Swedish People's Party of Finland (SFP). During the Continuation War, he was among the signatories of the "Petition of the Thirty-three", which was presented to President Ryti on 20 August 1943 by members of the Peace opposition.