Mister G may refer to:
- King Gustaf V of Sweden, playing tennis under the pseudonym Mister G
- Mister G (children's performer)
- Mr G, a fictional character in Summer Heights High portrayed by Chris Lilley
- Mr g, a 2012 novel by Alan Lightman
- Irv Gikofsky, better known as "Mr. G", weatherman serving the New York City metropolitan area