Seymour

Seymour drives a space taxi and carries whoever pays, which in the Galaxy of Limbo means carrying some very bad people. Twenty-four episodes make him the most-used civilian in the series, ahead of several Mob regulars.

The show is clear-eyed about his business. He struggles for fares because almost everybody in Limbo owns a ship, so he takes what he can get. His neutrality is real rather than a pose: in Zero The Memory Thief he unwittingly ferries Zero to Hawk Haven, and in Magnetic Attraction he switches sides mid-scene and uses a polarity reversal device to free the Steel twins, purely because Hardware and Mumbo Jumbo were rude to him.

His catchphrase is recorded two ways, as “You know what I mean?” on the ThunderCats wiki and “Y’know what I mean?” on thundercats-ho. His species is never named. He predates Zeek by seventeen episodes, and the pairing everyone remembers only starts at Hotwing Hits Limbo.

Voice. Wikipedia and thundercats-ho.fandom both credit Peter Newman. The ThunderCats wiki, which is usually the more willing to name an actor, leaves the field empty.