Nutley played for Queensland in this year's State of Origin

Nutley, who played for Queensland in the 2005 State of Origin series, was released from the final year of his Cronulla Sharks deal.

The 31-year-old has played in Super League before, making 99 appearances for Warrington between 1998 and 2002.

Manu, 25, played 14 times for St George Illawarra Dragons this year.

The Tonga international, who is a non-quota player, has had previous spells in Australia's NRL with Wests Tigers and South Sydney.

Both are just the type of quality players that we have been looking to bring to the club Castleford chief executive Richard Wright

"We believe that these are two excellent acquisitions for the Tigers who will add strength and toughness to our pack," Castleford chief executive Richard Wright.

"We have had to work very hard to bring the duo to the club, with (new coach) Terry Matterson playing a big part, as both were first-team regulars and under contract.

"Danny capped a tremendous season this year with State of Origin selection and Willie is a regular in the Tongan set-up, and both are just the type of quality players that we have been looking to bring to the club."

Manu and Nutley join Danny Sculthorpe, Matt Whitaker, Andy Bailey and Keith Mason as new signings at The Jungle.

St Helens' Welsh international prop Keith Mason joined on a 12-month loan on Wednesday.