Aethis

Aethis the Poet was elected the eighth Phoenix King of Ulthuan after the passing of Bel-Korhadris. He would be the second prince from Saphery to attain the crown.

History
During his rule, art bloomed and music was heard through Ulthuan, combined with a great sense of joy, as rumours spread that the Dark Elves were all but extinct and Malekith himself had finally died. It was during this time that the shrinking number of births was first noted and that the Elves were diminishing. During this time, Dark Elf infiltrators snuck back into Ulthuan and the Cults of Pleasure spread once more: in the end, several Swordmasters of the White Tower of Hoeth were sent to investigate, and a long and bloody war was waged in secrecy between the Swordmasters and the cultists. Ultimately, Aethis’s High Chancellor, Girathon, was unmasked as a Dark Elf spy. Girathon chose to fight rather than come quietly, and in the struggle drove a poisoned dagger into Aethis's chest. Thus was the Phoenix King slain by an Elf he'd trusted as a friend.

Source

 * Warhammer Armies: High Elves (4th Edition) -- pg. 7, 16-18.