John Robert Dimmer (born 19 November 1954[2]) is a former Australian rules football coach and player from Western Australia.

In 1994, he coached the West Coast Amateur Football Club, winning the WAAFL A Grade premiership and receiving the JJ Leonard Medal as a personal achievement.

He continued coaching the Falcons until the end of the 1999 season, during which he led them to a second Grand Final win, defeating South Fremantle in the third year in which the competition was known as "Westar Rules".

In 2004, he began coaching South Fremantle, leading them to a premiership the following year in a convincing Grand Final win over Claremont after finishing second during the home-and-away season.

In 2017, he received the AFL Coaches Association's Lifetime Achievement Award, which recognises "an individual who has made an outstanding contribution" to the sport of Australian rules football.