Horsemen of the Apocalypse/WMG

The 4 Horsemen are video game characters.

 * Death (the Pale Horseman) is John-117. Hence the 2 Halo songs "On A Pale Horse" and "Behold A Pale Horse", one of which plays during the flight section on "The Covenant" in Halo 3. Yes, 117 is Death.
 * War (the Red Horseman) is
 * Alternately, Sid Meier. That broody bloke from Darksiders might be in the running, too.
 * Another option is Mario, Rider of the Red Yoshi.
 * Civil War (the White Horseman) is James Raynor.
 * And Pacman, who devours everything remotely edible in a region before moving on to the next, is Famine.

The Chaos Gods are the Four Horsemen.

 * OK, so Khorne = War, Nurgle = Pestilence. Easy peasy. Assuming that we have Strife (or Satan) instead of Death, Tzeentch fits pretty well. And, er... Famine is the Horned Rat, who got sick of the others and went off to start his own religion, so they replaced him with an exchange student from the Anthropomorphic Personifications of the Seven Deadly Sins, Slaanesh = Lust.
 * Although having mentioned Skaven, Eshin = Death, Pestilens = Pestilence, Skryre = War and Moulder = Famine works much better...
 * And how does Kaos fit in?
 * He doesn't, he's Kaos.
 * Alternately, if we're going by the horsemen that actually appear in Revelation, Slaanesh = Conquest, Khorne = War, Nurgle = Famine and well... In Tarot, the Death-card represents change, so Tzeentch is obviously Death.

The four horsemen are exactly that
Meaning a Half Human Hybrid with horses.
 * Centaurs?

The four horsemen will be replaced.
Dr. Bright said it himself: "Screw War, Famine, Death, and Pestilence, We've Got Clef, Fishmonger, Kondraki, and Bright!"
 * But Fishmonger's gone, leaving...?

The identities of the horsemen.

 * Conquest- Chuck Norris.
 * Famine- Mr.T
 * War- Bruce Lee
 * Death- a minigun-weilding Abraham Lincoln