Gian Robert J. Mamuyac (born March 5, 1999) is a Filipino professional basketball player for the Rain or Shine Elasto Painters of the Philippine Basketball Association (PBA).
Mamuyac was selected 5th overall pick by the Rain or Shine Elasto Painters in 2022 PBA draft. As a rookie, he earned his first PBA All-Star Game selection in 2023.
As of the end of 2024âÂÂ25 season
|- | align=left | | align=left | Rain or Shine | 30 || 21.8 || .432 || .269 || || .744 || 3.0 || 2.1 || 1.1 || .2 || 9.9 |- | align=left | | align=left | Rain or Shine | 29 || 22.0 || .494 || .222 || || .681 || 2.8 || 2.4 || .9 || .2 || 10.7 |- | align=left | | align=left | Rain or Shine | 44 || 24.8 || .370 || .160 || .000 || .807 || 3.4 || 2.6 || 1.1 || .3 || 10.3 |-class=sortbottom | align="center" colspan=2 | Career | 103 || 23.1 || .421 || .217 || .000 || .759 || 3.1 || 2.4 || 1.0 || .2 || 10.3