Nope, not Maeglin, son of Eol. Maeglin also is not of the race of men. His brother-in-law also is not Arvedui, the last king of Arthedain
Maeglin convinced Turgon not to sally his forces and defend behind the walls of Gondolin. Though he did fight in the Nirnaeth, not serving as regent in case King Turgon died, he survived.
Here's another hint: Somebody in Lord of the Rings has the same name as the riddle's answer (but different fathers).