Isaak Khristoforovich Lalayants (pseudonyms: Columbus, Izarov, Insarov et al.; 5 August [O.S.
24 July] 1870, Kizlyar, Russian Empire – 14 July 1933, Moscow, Soviet Union) was a Russian revolutionary, Marxist, Bolshevik and comrade-in-arms of Vladimir Lenin.
He was a member of the Russian Social Democratic Labour Party (RSDLP) since 1898 and member of its Central Committee from 1905 to 1906.