Raiden is one of the central characters of the franchise. Based on the Japanese thunder god, Raijin, and portrayed in the series canon as the thunder god and appointed protector of Earth, Raiden defends the planet from myriad otherworldly threats alongside his handpicked warriors. He commands many supernatural abilities such as teleportation, flight, and control of the elements.
While there are many voices for the ol' thunder god, there were only a few credited as the actual voice and not the "motion capture" actor for the character.
For the (rather shoddy) tie-in animated film to the live action movie, Ron Feinberg voiced Raiden. There isn't much I can say, since his role in the movie was basically exposition, but he gives an appropriately wise performance. Nothing to really remember him by at all, though.
In Defenders of the Realm, Kurgan himself, Clancy Brown, dons the straw hat. While he's not a bad choice for a god and the voice is his standard voice, the material given makes him sound ridiculous in a cheesy way. I really think this is probably one of the best cast choices in the show, it just really didn't feel fully realized. Wouldn't mind a reprisal with some more dignified material. That, and Clancy sounds like he didn't give a damn about anything.
Richard Epcar, the most consistent voice for Raiden running for over a decade, does not disappoint. His sheer gravitas and material in the subsequent games properly shows the Thunder God as a mighty force to be reckoned with. Richard, don't ever change your Epcar.