In search for the face that launched a thousand ships (yep, still Troy :-)
This is not one of Helen's many depictions, though :-)
The Iliad offers little help for casting directors. The Homeric text seldom describes what Helen looks like. (When it does, she's "white-armed" and garbed in "shimmering linen.") Instead, the poem attends closely to how men respond to her. When Helen first appears, the Trojan elders murmur: "No wonder the men of Troy and Argives under arms have suffered years of agony all for her, for such a woman. Beauty, terrible beauty! A deathless goddess—so she strikes our eyes!" A Greek man, listening to a bard sing these lines after dinner, was free to lean back and imagine his own version of extraordinary, unsettling beauty. Legend has it that Homer was blind, so sculptures of him tend to have an uncanny expression: It looks as though he, too, is picturing something unfathomable in his mind's eye.
See here a slideshow of depictions, drawn from History, Art and Cinematography.