The eight Grandmasters of MMA

The nice thing about the Elo ratings used in chess is that they can be applied to many different games and sports, including MMA.  In chess, becoming a Grandmaster requires achieving an Elo rating of at least 2500 at some point in the player's career.  Only eight fighters in the history of MMA have done this.

daniel-cormier
georges-st-pierre-rush
rafael-dos-anjos
chris-weidman
stipe-miocic
jon-jones-bones
12723-max-holloway-lil-evil
tyron-woodley-t-wood

The bad thing about Elo ratings is that they are subject to inflation, so great fighters from the past had little chance of achieving Grandmaster status.  Some, however, have earned lesser titles.

International Masters (highest all-time Elo rating between 2400 and 2500):

jose-aldo-junior
fabricio-werdum-vai-cavalo
luke-rockhold
17398-robert-whittaker
16155-yoel-romero-palacio
robbie-lawler-ruthless
michael-bisping-the-count
14607-conor-mcgregor
anderson-silva-the-spider
anthony-johnson-rumble

Masters (highest all-time Elo rating between 2300 and 2400):

19126-tj-dillashaw
demetrious-johnson-mighty-mouse
16753-stephen-thompson-wonderboy
cain-velasquez
alistair-overeem-demolition-man
fedor-emelianenko-the-last-emperor
demian-maia
ben-henderson-smooth
gegard-mousasi-the-dreamcatcher
18536-khabib-nurmagomedov
eddie-alvarez-the-silent-assassin
ronaldo-souza-jacare
edson-barboza-mendes-junior
rory-macdonald-the-waterboy
frankie-edgar-the-answer
donald-cerrone-cowboy
tony-ferguson-el-cucuy
anthony-pettis-showtime
nate-diaz
johny-hendricks

Candidate Masters (highest all-time Elo rating between 2200 and 2300):

alexander-gustafsson-the-mauler
dominick-cruz-the-dominator
ben-askren-funky
nick-diaz
21780-cody-garbrandt-no-love
jorge-masvidal-gamebred
phil-davis-mr-wonderful
ryan-bader-darth
hector-lombard-shango
16456-aoutneil-magny
18069-andrey-koreshkov-spartan
carlos-condit-the-natural-born-killer
dan-henderson-hollywood
patricio-freire-pitbull
chad-mendes-money
junior-dos-santos-cigano
rousimar-palhares-toquinho
jake-shields
douglas-lima-the-phenom
vitor-belfort-the-phenom
renan-barao-barao
23860-kevin-lee
14206-will-brooks-ill
41355-kelvin-gastelum

The database I'm using contains 13,409 fighters, so achieving any of the above titles is an incredible accomplishment, and it's worth examining exactly how the top eight--the Grandmasters--obtained their unbelievably high ratings.

Max Holloway achieved Grandmaster status with a victory over Master Anthony Pettis, followed by a victory over International Master Jose Aldo.

Chris Weidman achieved Grandmaster status with two consecutive victories over International Master Anderson Silva.

Stipe Miocic achieved Grandmaster status with consecutive victories over International Master Fabricio Werdum, Master Alistair Overeem, and Candidate Master Junior Dos Santos.

Daniel Cormier achieved Grandmaster status with two victories over International Master Anthony Johnson and a victory over Candidate Master Alexander Gustafsson.

Tyrone Woodley achieved Grandmaster status with a victory over International Master Robbie Lawler, followed by a victory over Master Stephen Thompson, followed by a victory over Master Demian Maia.

Rafael Dos Anjos achieved Grandmaster status by defeating four Masters in a row: Benson Henderson, Nate Diaz, Anthony Pettis, and Donald Cerrone.

Jon Jones achieved Grandmaster status by defeating Candidate Master Alexander Gustafsson, followed by a victory over Glover Teixeira, followed by a victory over Grandmaster Daniel Cormier.  Jon Jones is the only Grandmaster who has defeated another Grandmaster.

Georges St. Pierre achieved Grandmaster status with a victory over Candidate Master Jake Shields, followed by a victory over Candidate Master Carlos Condit.  Subsequent victories over Candidate Master Nick Diaz, Master Johny Hendricks, and International Master Michael Bisping took him to the highest Elo rating in MMA history, 2,604.