Bishop Demetrius Martin Greschuk (Ukrainian: ?????? ?????? ??????; 7 November 1923 in Innisfree, Alberta, Canada – 8 July 1990 in Edmonton, Canada) was a Canadian Ukrainian Greek Catholic hierarch.
He served as the Titular Bishop of Nazianzus and Auxiliary Bishop of Ukrainian Catholic Eparchy of Edmonton from 27 June 1974 until 28 April 1986 and as the second Eparchial Bishop of Ukrainian Catholic Eparchy of Edmonton from 28 April 1986 until his death on 8 July 1990.