Mobar impersonating Tuvok
Mobar was an alien con artist who impersonated the Starfleet Lieutenant Commander Tuvok in a con in conjunction with his partners Dala and Zar in 2376.
Using this deception, he and his partners were able to move from system to system offering services for different goods from the various races, but not delivering what they promised. Eventually, USS Voyager caught up with the three and captured them, returning everything they stole.
Mobar took quite a liking to Tuvok and his Vulcan mannerisms – going so far as to remain in character even when just among his fellow con artists – and felt privileged when he met the real Tuvok. When faced with a stand-off of drawn phasers with the real Tuvok, Mobar commented that "logic would indicate" that neither had the advantage. Tuvok, unamused by Mobar's sendup of Vulcan behavior, promptly blinded him with the beam of a SIMs beacon and phasered him. (VOY: "Live Fast and Prosper")