Welsh captain Dan Biggar will leave Northampton at the end of the 2022-23 season after five years with the Premiership club.
Biggar, 32, joined Ospreys in 2018 and will leave at the end of his current contract.
The British and Irish Lions fly-half is unsure where he will move next.
“I loved my time at Northampton Saints, a traditional rugby club full of great people from top to bottom,” said Biggar.
The Welsh fly-half is set to start his new club career after the World Cup in France next year.
“I wish I could have played more for the club,” added Biggar.
“I’ve missed a few games over the last few years due to my international commitments, but there’s no better place to play rugby than Franklin’s Gardens in front of an incredible group of supporters.
“I’ve made new friendships that will last forever, and it’s been a pleasure to watch the younger generation of academy lads mature into senior first-team pros.
“There are too many brilliant people here to mention, but hopefully we can all end the season spectacularly like we did last year, and go even further.”
Biggar singled out former director of rugby Chris Boyd, who left the club earlier this year, for special praise.
“I can’t thank him enough for the way he treated me and gave me so many opportunities to represent this club,” Biggar added.
“The Saints will always be very special to me – and that includes the wonderful supporters of the club, who have welcomed and wholeheartedly supported me through ups and downs. It has been a privilege.”
Biggar, who started all 68 games he played for Northampton, helped Saints to a top-four finish in the Premiership in four seasons.
“Dan’s quality as a player is evident,” said director of rugby Phil Dowson.
“He’s a British and Irish Lion, a 100-cap Welsh international, a leader who cares about the team.
“He likes pressure and he likes competition. His attitude is also exemplary.
“When he arrived at the Saints in 2018, we were a club in transition and a lot was expected of him.
“He played a major role in rebuilding the team.
“We are now at a point where we feel we should be competing on the business side of major competitions, with a number of leaders within the team having just arrived when Dan arrived.
