Tillie Martinussen (born 1980) is a Greenlandic politician of the Cooperation Party. She was a member of the Inatsisartut, Greenland's parliament, from 2018 to 2021. She helped form the Cooperation Party in 2018, and was the only member of the party to be represented in the Inatsisartut from that year's election; she did not return to parliament after the 2021 election. She is an opponent to Greenlandic independence.