Aaron
Aaron was a Mobian Echidna, the son of Rembrandt and brother of Jordan. He has the distinction of being the first Guardian of Angel Island to die childless, and before joining the Brotherhood of Guardians. As the last Guardian trained without the restrictions his father Rembrandt instituted after his death, he was fully aware of the continued existence of his predecessors as Guardians. On his third trip to Mobius Prime, however, Aaron ran afoul of Dark Legion Grandmaster Menniker and a group of Overlanders with plans to launch a missile at Angel Island. Leaping atop the missile, Aaron attempted to disarm it, only to be attacked by Menniker. When his distant relative cautioned him not to depress a particular switch, Aaron defiantly did so anyway, detonating the missile and killing them both. After grieving for his son, Rembrandt came up with the Brotherhood code of secrecy that continued until the time of Knuckles. (KtE: #25)
Aaron was present along with the rest of the deceased Guardians who met with Knuckles in the afterlife. (StH: #121)