Millington, a former prop forward for Cronulla, has signed a permanent two-year deal with the club whilst back-rower Mitchell has initially signed on a one-year deal with the view of signing on a permanent basis if both clubs agree at the end of 2012.
Standing at 6ft 4in, 25-year-old Millington came highly recommended and Tigers boss Ian Millward told local press: “Grant likes to charge the ball in and tackle aggressively, he’s tough but he does have some skill, he has a pass to his game and an offload as well.
“He brings variation to our attacking game up front and he comes highly recommended by Ricky Stuart, his former coach at Cronulla, and also Trent Barrett who played with him there.
“He had a contract with the Canterbury Bulldogs for 2012, but he had a shoulder reconstruction during the year and because of that he missed a lot of games last season.
“It is more than likely he will miss the first couple of games, but I’m looking at the bigger picture with him. He played in all but one game for Cronulla in 2010 and we’ve covered every base with his medical; he’s well on his way to a full recovery.
“Hopefully we’ll be playing over 30 games next year and him missing the first couple shouldn’t be the main issue. I’m confident he’ll be a good signing for us.”
Meanwhile 21-year-old Mitchell is no stranger to Millward after the Tigers boss coached him whilst at Leigh Centurions “Such is the quality and depth of the Warrington squad, it is definitely in Lee’s interests to continue to improve his game by playing for us.
“He is ready for the rigours of Super League week-in-week-out and is an extremely talented English back row. He comes with height and has lots of mobility, plenty of skill and a fantastic attitude.
“He spent a short period with me at Leigh last year and that is where my association with him started. There’s mutual respect and I’m delighted to be able to bring him to Castleford.
“He adds depth to our squad and he’s hungry to play. Although not guaranteed a spot, he’ll get opportunities here with us next year.”