Rob Harley, Glasgow Warriors' record appearance holder, will leave the United Rugby Championship side this summer after 12 years.
The forward, 31, has featured at lock and flanker across 260 Warriors matches.
Harley has won 23 Scotland caps and scored his only international try on his debut against Samoa in 2012.
"A huge chunk of my life has been with Glasgow Warriors, and it's been an amazing experience," he said.
Crewe-born Harley made his Warriors debut against Leinster in September 2010 and surpassed the previous record mark held by Graeme Morrison when he made his 178th appearance in February 2018.
"There are so many memories," added Harley. "Winning the [2015 Pro12] title was hugely special, but it's hard to pick just one, having played with so many great teams.
"I'm looking forward to coming back to Scotstoun [Stadium] one day as a fan and standing with the fans who have been so good with me over the years, cheering the team on from the stands.
"For now, though, I'm looking forward to finishing my Glasgow career on a high, but also excited about the next step of my playing journey and experiencing something different, wherever that may be."
Head coach Danny Wilson added on Glasgow's website: "Rob Harley is an outstanding professional whose service to this club is second to none."