Gary Muller (born 27 December 1964) is a former professional South African tennis player.

His 12-year career included wins over Andre Agassi, Jim Courier, Michael Chang and Stefan Edberg.

Muller's best singles result at a Grand Slam was reaching the third round in the 1987 Australian Open in which he lost to Miloslav Mečíř of Czechoslovakia.

[1] After his retirement in 1997 Muller worked for eight years as an ATP Tour coach during which time he worked with Jonas Björkman, Stefan Koubek, Sargis Sargsian and Thomas Johansson.

He was with Dominic Thiem as his Touring Coach when he clinched the title in Rio in 2017.