Urabe Kousetsu

Urabe Kousetsu is a male member of the Holy Sword of Kyoto and later the Black Knights. He is the first to accept Zero and is one of the few to escape being captured following the failed first rebellion. At the start of Season 2 he is still with the Black Knights and knows about Lelouch's identity but probably not Geass.

Spoiler

When Rolo attacks the Black Knights he sacrifices himself to let his comrades escape.