UFC Hall of Famer Stephen Bonnar, who appeared on Impact Wrestling and also challenged Nick Aldis for the NWA Worlds Heavyweight Championship last year, passed away on Thursday at age 45 of presumed heart complications, according to UFC.

Bonnar vs. Griffin the UFC Ultimate Fighter Season 1 finale is considered one of the best fights in MMA history and is considered the fight that forever changed UFC's history for the better, cementing The Ultimate Fighter and UFC forever.

After retiring from UFC in 2014, Bonnar began training for professional wrestling and began making independent appearances in 2017. He debuted in 2017, competing for NYC's House of Glory, defeating Sho Tanaka. He made appearances for a number of promotions on the West Coast, including BTW, PCW Ultra and New Mexico's DWO. Over the course of his run in independent wresling, he faced Speedball Mike Bailey, MVP, Wes Brisco and Matthew Justice, among others.

Bonnar also made a number of appearances for Impact Wrestling. At Bound for Glory 2017, he and Moose teamed against Bobby Lashley and King Mo, losing in a Six Sides of Steel match. In 2019, he returned as part of Moose's feud with Ken Shamrock, defeating Moose on an episode of Impact on AXS. The two rematched at the Victory Road 2019 PPV with Moose scoring the win.

Bonnar last wrestled in August 2021, unsuccessfully challenging then-NWA Champion Nick Aldis on a Minnesota All-Star Wrestling card in Stillwater, MN.

UFC's statement on Bonnar's passing.

Everyone at PWInsider.com sends our deepest condolences to Stephan Bonnar's family, friends and fans.