Amergin

Amergin was the High Druid of Avalon and was its sole defender against the threat of the extra-dimensional Fomor. In 1194 CE Amergin, with the help of the the modern heroes the Black Knight and the Avengers, who had traveled back in time, managed to defeat the Fomor. Amergin was instrumental in getting the Black Knight's spirit back into his modern body; he'd been trapped in the body of his 12th century ancestor before this. Amergin died in battle against the Fomor.