Graham Keith Ernst (born 16 March 1940) is a former Australian politician.
He was born in Yorketown, South Australia, to Frederick Ernst and Leta Grace Ochtomann. He attended state schools in Cranbrook and Portland before becoming a fitter and turner. He also worked as the manager of a bakery and as a shop steward. Heavily involved in the union movement, he was founding junior vice-president of the South West Trades and Labour Council and a branch president of the Amalgamated Metal Workers Union. He moved to Geelong in 1973, where he became president of the Geelong Amalgamated Metal Workers and Shipwrights Union and junior vice-president of the Geelong Trades Hall Council. In 1979 he was elected to the Victorian Legislative Assembly as the Labor member for Geelong East, moving to Bellarine in 1985 following his old seat's abolition. He was defeated in 1992.