One of the seven sons of Feanor, a minor character in Tolkien's The Silmarillion
. Often listed along with Celegorm and Curufin, but absent from the account of the kidnapping of Luthien, he died along with this pair while assailing Elwing's forces.
If there's seven, and they're all in pairs, there has to be an odd one out, right? And it's this guy.