Oklahoma City Thunder forward/center Nick Collison announced his retirement on Thursday, closing the chapter on a 15-year NBA career, according to ESPN's Royce Young.

General manager Sam Presti offered a heartfelt farewell to a key cog in the organization via Fred Katz of The Norman Transcript.

“Sometimes, in the early phases of an organization's life cycle, the right player comes around at the right time to help define their vision,” said Presti. “For the Thunder, Nick Collison was one of those players. Nick has helped define the standards we work by on a day-to-day basis, on and off the court and has become synonymous with the Thunder shield.”

Collison was part of the legendary 2003 NBA Draft, not a highly-touted as prep stars like LeBron James or college champions like Carmelo Anthony, but a 12th overall pick by the now-defunct Seattle SuperSonics out of the University of Kansas.

The Iowa native went to two Final Fours with the Jayhawks, only to miss his entire rookie season with injuries to both shoulders.

Upon the team's relocation to Oklahoma City in 2008, the now veteran Collison lost some of his prominence with the team, despite riding a scoring average short of double digits in the previous two seasons.

russell westbrook, nick collison
Sue Ogrocki/The Associated Press

Collison instead took the part of a glue player, watching the likes of Kevin Durant, Russell Westbrook, Jeff Green, and James Harden grow into stars in their own right.

The longtime veteran narrated his very own story, giving insight on the highs and lows he experienced throughout his career.

“It was our second year in Oklahoma City, coming off a 23-59 debut season, one we started 3-29 and had people wondering if we were the worst team of all time,” wrote Collison.

“But this was different. I'd played one season already with Kevin Durant, but he was getting really good. Russell Westbrook was still trying to dunk everything, but he was getting better. James Harden was our new draft pick, and even though he'd just gotten here, he already knew what to do.”

It was Collison, who many revered as their best teammate; the eyes that saw it all — from the ghost of Gary Payton to Ray Allen's brightest statistical seasons, to the eventual transformation that the franchise underwent.

Collison saw the birth of a star in Durant, the start of a phenom in Westbrook, and the untapped potential in Harden. Now at the end of a 15-year run, the 37-year-old has decided to hang them up.

“I've had the privilege of being one of the guys on a basketball team for a long time. I've loved the friendships and appreciated the camaraderie. There is nothing better than being on the road and going on a run in the fourth quarter to put a game away, then going out with all of the guys after.

I've had a lot of those nights.

I won't get to feel that fire or that rush anymore, but I do get to keep the memories, the stories and the relationships. That's what I will cherish the most. Things worked out for me.

I got to stay here a long time, but now it's time to go.”