Ferdinand Teodor Kettunen (18 January 1889, Saint Petersburg – 31 August 1920, Petrograd) was a Finnish communist activist.^[1]

Kettunen was born in Saint Petersburg, where he worked in the steel industry. He was already active in underground movements from 1905.^{[citation needed]}

Kettunen was also an active member of the Russian Social Democratic Labour Party from 1906. In 1920 he became the steward of the Finnish Communist Party's military organization.^{[citation needed]} Kettunen was one of the victims of the Kuusinen Club Incident in Saint Petersburg in 1920 when radical Finnish communists killed eight members of the Communist Party in a power struggle.^{[citation needed]}

Kettunen is buried at the Monument to the Fighters of the Revolution on the Field of Mars in Saint Petersburg and his name is found located on the grave of the August Communards.^{[citation needed]}