Huddersfield say centre or second rower Lee Gilmour has played his last match for the club.
The 34-year-old former Wigan, Bradford, St Helens and Great Britain player, who is joining Castleford on a two-year contract from next year, has been ruled out for the rest of the season with a shoulder injury which will require surgery.
"It's unfortunate for him as he is a proud man and a true professional," said Giants coach Paul Anderson.
"All being well, the surgery will prove a success and he'll make a full recovery.
"Lee intends to stay around the squad once the operation is done and give us his full support from the sidelines."