Cook began his career at union side Saracens
Hull Kingston Rovers have signed forward Matt Cook from Bradford Bulls on a two-year contract from 2010.
The 22-year-old leaves the Gratton Stadium after six years and Robins coach Justin Morgan is delighted to capture the former rugby union convert.
He told BBC Radio Humberside: "Matt's a player that's got a tremendous amount of experience for his youthfulness.
"He's going to add a punch to our back row but has played front row and he has a great attitude."
Cook, who will be 23 in November, started out as a rugby union player at Saracens but switched to rugby league at the age of 16, when he signed for Bradford and made his debut for the club in 2005.
He is Rovers' first new signing for next season and Morgan believes the forward will only get better at Craven Park.
"He's a great edge runner, we've got a very similar player in Clint Newton and Matt increases our options in the back row," he said.
"He's got great leg drive and speed and he adds another dimension to or squad."