Ian Denys Turnbull (born July 1, 1935 in Winnipeg, Manitoba) is a politician in Manitoba, Canada. He was a New Democratic member of the Legislative Assembly of Manitoba from 1969 to 1977, and a member of Edward Schreyer's cabinet from 1973 to 1977.

Turnbull was educated at the University of Manitoba, and worked as a teacher. He was first elected to the Manitoba legislature in the provincial election of 1969, defeating Progressive Conservative incumbent Obie Baizley by 623 votes in the central Winnipeg riding of Osborne. He was not appointed to cabinet in Schreyer's first term, but was made a Board Member of the Manitoba Telephone System in 1970.

He was re-elected in the 1973 election, defeating Liberal June Westbury by 1598 votes. On July 4, 1973, he was named Minister of Consumer, Corporate and Internal Services with responsibility for the Manitoba Telephone System . Following a cabinet shuffle on September 22, 1976, he was promoted to Minister of Education .

In the 1977 election, he lost to Tory candidate Gerald Mercier by 96 votes. He has not sought a return to politics since this time.