Young
Young was the persona of a Starfleet officer assumed by a member of Species 8472 in 2375, who trained at Terrasphere 8 for infiltrating the Federation.
In that recreation, Young and his comrade Reiskin were assigned to Orbital Flight Control by Admiral Bullock to monitor incoming ships from the Bolian sector. (VOY: "In the Flesh")
It is unclear if there is a real Young in Starfleet or if the persona was created by Species 8472.