Cassiel Emmanuel Rousseau is an Australian diver. He competed in the 2020 Summer Olympics in the men's 10 metre platform, and the 2024 Summer Olympics in the men's 10 metre platform and men's synchronised 10 metre platform, the latter with Domonic Bedggood. Rousseau claimed gold in the men's 10m platform World Championships event in Fukuoka 2023, creating history for the Australian diving team by becoming the first Australian men's 10m platform world champion.