Western Force flanker Steve Mafi is one of seven signings confirmed by Top 14 side Castres.
Forward Mafi has agreed terms on a two-year deal with the option of a third season at the four-time French champions.
The 26-year-old Australia-born Tonga international will be joined by Chiefs back-row Ma'ama Vaipulu on a two-year contract ahead of the 2016/17 campaign.
Back Robert Ebersohn has agreed to make the switch from Top 14 rivals Montpellier, while Albi centre Afusipa Taumoepeau is another recruit for Castres.
Clermont Auvergne's Daniel Kotze has also opted to move to Castres, along with fellow props Damien Tussac and Tudor Stroe from Montauban and Tarbes respectively.