From Robert Jordan's The Wheel of Time series of books.
In the Age of Legends, Balthamel (then called Eval Ramman) was a historian and a lecher before turning to the Shadow and becoming one of the Forsaken. During the War of the Shadow he ran a spy network for the Dark One and was bound with the rest of the Forsaken by Lews Therin Telamon when he made his strike at the Bore.
When freed in this Age, he was killed by the Green Man at the Eye of the World in battle, but has since been recycled by the Dark One into the body of an attractive woman called Aran'gar, who has infiltrated the rebel Aes Sedai and is serving as Egwene's maid called Halima.