Siba Mahashe (born 11 April 2004) is a South African rugby union player, who plays for the . His preferred position is flanker or number 8.
Mahashe is from South Africa and attended Hudson Park High School. His performances earned him selection for the Border side at Craven Week in 2022, earning him selection for the South Africa Schools side in 2022, captaining the side on two occasions. He joined up with the Lions academy in 2023, being named in the SA Rugby academy in 2023, and captained the Lions U21 in 2024 and 2025. In 2024, he earned selection for the South Africa U20 side.
Mahashe joined up with the first team in early 2026, being named as an additional player for the 2025âÂÂ26 EPCR Challenge Cup. He would debut for the Lions in Round 3 against . He would then debut in the URC against the scoring on his league debut.