UFC fighter Allan Nascimento has died at the age of 34, the promotion announced. The Brazilian mixed martial artist died in his sleep after a suspected heart attack, according to the UFC. Former NFL quarterback Robert Griffin III was among those who paid tribute, posting condolences on X for Nascimento's family and friends. Nascimento competed in the flyweight division and was known for his grappling skills. The UFC's announcement confirmed the death but provided no further details. Tributes began surfacing on social media following the news, with Griffin III's message highlighting the impact of the loss on the fighting community.