As of April 2019, there have been seven recorded deaths resulting from sanctioned Mixed Martial Arts contests and nine from unregulated bouts, none however in the largest MMA promotion Ultimate Fighting Championship.
However, they are some incidents in which fighters have sustained life-threatening injuries, or in the worst case have died, so the question remains, has anyone died in the UFC? and the answer is no, but there are 7 recorded deaths in sanctioned fights outside of UFC.May 24, 2021
Does UFC Use Different Size Octagons? As already mentioned, not all of the UFC Octagons are the same. In most cases, UFC uses their usual Octagon of a diameter of 30 ft (9.1 m). Sometimes, during the smaller events, they use an Octagon of a diameter of 30 ft (9.1 m).