MMA fighter and UFC star Elias Theodorou has tragically passed away at the age of 34.

The mixed martial arts world is mourning the loss of the Canadian fighter, who fought his last professional match against Bryan Baker on December 18, 2021, in the Colorado Combat Club 10 event.

The Daily Mail reports that the middleweight fighter died of cancer, with the fighter choosing not to make his battle with the illness public.

Theodorou died on Sunday, September 11, after being diagnosed with stage 4 liver cancer.

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While studying for his BA degree in Creative Advertising at Humber College, Theodorou started taking MMA classes, and eventually opted to pursue the sport as a career.

During his time in the UFC, he won eight of his 11 fights - defeating the likes of Cezar Ferreira, Dan Kelly, and Trevor Smith. He would ultimately go on to be ranked 13th in the UFC, but departed the UFC after Dana White claimed it would be unlikely for him to become a top five fighter following his loss to Derek Brunson on May 4, 2019.

Throughout his professional MMA career, Theodorou boasted a 19-3 record, with eight of his victories coming by knockout.

News.com.au also reported that Theodorou was the first professional athlete in the US to be granted medical exemption for the use of cannabis.

Following Theodorou's passing, Dana White led tributes on social media, sharing an image of the fighter to his Instagram Stories, along with the caption: "RIP Elias Theodorou".

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TSN MMA reporter Aaron Bronsteter also took to Twitter to say: "Sadly, a representative of Elias Theodorou has confirmed earlier reports that he has passed away at age 34.

“Theodorou was privately battling Stage 4 liver cancer and had only told a select group of people of his diagnosis."

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Bronsteter's post continued: "Securing the Therapeutic Use Exemption was a years-long quest that he dedicated his time and resources towards and his legacy for cannabis athletes will be felt for years to come. RIP Elias. A great athlete with a wonderful sense of humour and a smile that would light up a room."

UFC welterweight star Michael Chiesa also shared an emotional video paying tribute to Theodorou - recalling how his friend once literally gave him the shirt off his back.

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UFC Senior VP of Athlete Health and Performance Jeff Novitzky also took to Twitter to say: "RIP Elias Theodorou. A great person and a HUGE voice for the more fair and equitable treatment of marijuana use in MMA and sport."

Our thoughts are with Theodorou's family, friends, and fans at this time.

Featured image credit: ZUMA Press, Inc. / Alamy

UFC star Elias Theodorou dies aged 34