Guilherme Mendes Godoy (born 1988 in Rio Claro, São Paulo, Brazil) is a four-time Brazilian Jiu-Jitsu (BJJ) world champion at the black belt level.

Along with his brother Rafael, he started training Jiu-Jitsu through an older cousin named Thiago Mendes, who at the time was a purple belt under Leonardo Santos.

"Gui", as he is often called, is one of the main figures in the Atos Jiu Jitsu team, being also one of the best “peso pluma” (64,00 kg / 141.5 lb) competitors to have ever competed in the sport.

In July 2012, with the help of their long time sponsor and RVCA founder, Pat Tenore, Guilherme and Rafael Mendes opened up The Art of Jiu Jitsu Academy in Costa Mesa, California.

On October 6, 2020, the Art of Jiu Jitsu's famous kid's program produced its first black belt, eighteen-year-old Jessa Khan[2] followed that same month by Tainan Dalpra.