The champions lists have been updated through fights on Dec. 30.
Here's a look at the current and all-time UFC champions.
For more upcoming fights, go to the MMA schedule page.
Sonnen retires from MMA after loss to Machida
3dBrett Okamoto
Fedor signs 'retirement tour' deal with Bellator
3dMarc Raimondi
Dos Anjos-Edwards to headline UFC San Antonio
4dBrett Okamoto and Marc Raimondi
Khabib: McGregor doesn't deserve a rematch
6dGreg Rosenstein
UFC fighter sues after crane collapses into home
6dMarc Raimondi
Cerrone: No broken orbital, wants Ferguson again
6dMarc Raimondi
Sources: Andrade-Zhang match being finalized
6dBrett Okamoto
Bellator, Rizin proving cross-promotion healthy in MMA
6dMarc Raimondi
What we learned from PFL 3: Tiller's triumph, Magalhaes' stumble and more
11dMarc Raimondi, Jeff Wagenheim and Myron Medcalf
Bantamweight division gets shakeup from Cejudo, Sterling and Yan
546dBrett Okamoto
Waterson says Suarez is 'not ready for a championship fight'
7dGreg Rosenstein and Tim Fiorvanti