In The Wheel of Time
, Lews Therin Telamon -LTT for short- was known as The Dragon
. The name came from the scaly, serpent-like creature with wings on his banner. It is not known where this image came from, as even in his lifetime nobody had seen such creature.
Lews Therin was strong in One Power, one of strongest in his time, and a leading figure for the Light once the War of Power began. He loved Ilyena Sunhair, was loved by Ilyena and Lanfear (according himself, the feelings never were mutual with the latter) and was hated by and mutually hated back at least Demandred and Sammael.
It was him who led the Hundred Companions to Shayol Ghul to seal the Bore and thus reprison the Dark One. As interesting side note, Hundred Companions consisted entirely of men as female Aes Sedai (yes, there were male Aes Sedai at that time too) refused to join in for some reason, possibly to do with the dangerousness of the plan, not only for invading force but to the force. (see Shayol Ghul for more information on the subject)
And, indeed, Dark One was quite pissed off for the sealing. It is not known if it was just DO's power or did he somehow reflect the force LTT & pals used, but the DO managed to taint the saidin, which led to LTT, Companions and all saidin wielders to go insane, and with their insane powers (apparently, for some reason, LTT & Companions didn't die just channeling) began Breaking of the World, flattening a couple of mountains and moving some seas.
Lews Therin Telamon finally died, insane, after having killed everyone of his blood (earning his other name, Kinslayer), when Ishamael came, removed his insanity (that is still of great interest to the WoT world... just HOW did he do that? Could it be abused?) and in realization of what he had done, LTT rose a mountain (now known as Dragonmount) and destroyed himself. Whether it was Balefire or something else he used, is not known, however BF is unlikely as his deeds didn't get erased.
See also the Dragon, Dragon Reborn, Rand al'Thor.