*slight spoiler level*
In The Wheel of Time
, a male Forsaken
, possibly the greatest (in One Power
and in power
with minor p) of them all. He was also the second strongest channeler of his time, second only to Lews Therin Telamon
His real name was Elan Morin Tedronai, and his Forsaken-name is 'Betrayer of Hope' in Old Tongue. He was a philosopher in his time, believing that Lews Therin's battle with Shadow was of eternal nature, something happening with every turn of the Wheel or maybe even every Age. He was also the first to pledge his soul to the Dark One, and he has been rather fervent, if not religios about Shadow's cause ever since; other Forsaken have referred to him as 'insane', and some even suggested he actually believed himself to be the Dark One, or atleast the incarnation of LTT's counterpart in the Shadow (which might even be true).
Ishamael tried first to convert LTT, believing that this could be the key to Shadow's victory, which later proved true as it was LTT's fault (see darkfriend, kaatunut) that Bore got sealed. Ishamael himself believed that the Dragon's previous incarnations had succesfully been turned to the Shadow.
When Ishamael got bound, it was said he was not completely caught, or that his binding was of shallow sorts, that he saw the world. This might be true, as he has been witnessed to be seen a few times by Rand al'Thor in dream, however, it might just be that Ishamael had been freed a while ago as Aginor and Be'lal got freed in less than year from first appearance of Ishy in Rand's dreams. Ishy also claimed to have been at Artur Hawkwing's side, and he was detected with LTT when he went insane and killed himself. This happened at a time when Ishamael should've been bound already.
Ishamael called himself Ba'alzamon when introducing to Rand and his looks were kinda Dark One-ish, flaming eyes and all. Ba'alzamon was believed to be the Trolloc name for DO, meaning "the heart of the dark" and all (don't ask me how they learned Trolloc language), but it seems now that Trollocs knew Ba'alzamon to be Ishy all the way along. Still, Ishy claimed also to be Lord of the Grave, which clearly refers to Shai'Tan.
Whether Ishy truly was bound or not is unclear; it might be he travelled Tel'aran'rhiod from his prison, but some believe that he actually was bound later than others, enabling him to harrass LTT and was freed 2000 years before others, enabling him to harrass Artur Hawkwing (it also might be that he just lied... DO is also known as Father of Lies and he clearly believe himself to be DO) and to put some interesting plans in motion. Then again, if this was true then he could be considered real loser as in 2 years other Forsaken have accomplished huge things already. So it might be better just to believe him bound, and hard.