Hull FC have signed forwards Sika Manu and Danny Washbrook from Penrith Panthers and Wakefield Trinity Wildcats respectively.
World Cup-winning New Zealand international Manu, 28, has agreed a three-year deal.
Washbrook, 29, returns to the Black and Whites after three seasons at Wakefield and has signed a two-year deal.
"I've always watched Super League growing up and liked the physicality," Manu told the club website.
"I'm looking forward to a new challenge and now I am working hard to get ready for next year and finishing this season strong with the Panthers.
"I've played with a few of the boys who will be at Hull next year before and I'm looking forward to teaming up with them again."