Supreme Commander
From Halopedia, the Halo wiki
A Supreme Commander is the overall commander of a particular fleet; in the Halo Graphic Novel, he is depicted as clad in bright violet armor, with a long cloak that wraps around his shoulders. This particular Supreme Commander was a friend and superior to Rtas 'Vadumee, and would later become the Arbiter. Interestingly enough this same Commander wears gold Zealot armour in his trail at High Charity.
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