4. Jared Cannonier
Jared "The Killa Gorilla" Cannonier has a 17-6 record and holds wins across the UFC heavyweight, light heavyweight, and middleweight divisions but has still never held a championship. He has only challenged for the belt once, losing in that effort to then-reigning champion Israel "The Last Stylebender" Adesanya at UFC 276.
As of writing, Cannonier is ranked No. 4 in the UFC's middleweight division. He's earned his place beating top contenders like Marvin "The Italian Dream" Vettori and Derek Brunson. Early in his middleweight run, Cannonier even defeated longtime former champion, Anderson "The Spider" Silva. All this, including the fact he captured a tight split decision win over current middleweight champion, Sean "Tarzan" Strickland in the UFC's final fight night of 2022 makes Cannonier one of the most decorated fighters right now to not earn gold yet.
The only fighters to defeat Cannonier at middleweight are former champions, Robert "The Reaper" Whittaker and the aforementioned Adesanya. He put on valiant performances in both matchups, despite losing by a unanimous decision in each.
Cannonier remains one of the world's best middleweights and has proven to match well with the division's upper echelon of talent. He is capable of making another title run, but given that he's in his late thirties and there may be other matchups made before he gets his next chance- Cannonier remains one of the current best mixed martial artists to still not make it to the title.