In-form Steve Prescott has signed a new two-year contract with Hull.
The 29-year-old full-back is the leading points scorer in Super League with 11 tries and 59 goals, and is the current player of the month.
He has contributed so much to the club over the five years he has been a Hull FC player
"I'm delighted to be staying with the club and my family are very settled in Hull," said Prescott.
"It also means that I've got another two years at a fantastic club who are going places in Super League."
Hull coach Shaun McRae said: "It's a significant signing to be able to retain Steve's services for another two years.
"He has contributed so much to the club over the five years he has been a Hull FC player."
Andy Lynch has signed a contract extension that will keep him at Castleford until 2006.
The in-form prop was already contracted until 2004, but his performances this
season have earned him a two-year extension.
Tigers coach Graham Steadman said: "I am delighted with the progress that Andy has made and the consistency he has shown in his performances.
I'm very pleased to have signed a new deal with Cas.... I'm enjoying my rugby and it's a good place to be
"He is one of the top five props in Yorkshire and there is no reason why over the next few weeks that he can't push himself into the reckoning for an Origin shirt.
"I'm naturally very pleased that Andy has now committed himself to the Tigers.
"He has a bright future and his progress sends the right messages to our youth development structure that there is an opportunity here to work your way through to the top."
Lynch said: "I'm very pleased to have signed a new deal with Cas. I'm enjoying my rugby and it's a good place to be.
"We have done well to be fourth in the table half-way through the campaign and we've got a lot of youngsters who have been coming through the ranks this past 18 months.
"If that continues and we can continue to develop there is no reason why we can't retain that place and perhaps go higher."
Lynch, 23, graduated through the Tigers Academy after joining the club from Kippax juniors in 1996.