Agent

An agent is exactly what the title says: a functionary of some larger organization who shows up to investigate, contain, or interrogate whatever mess Rick and Morty have made. He speaks in the clipped, procedural language of officialdom, treating the show's cosmic absurdities as routine paperwork.

Chris Parnell's flat, faintly exasperated delivery is the joke — a voice built for sitcom normalcy dropped into interdimensional chaos and refusing to register the difference. The character works because he takes it all so seriously, which makes the surrounding lunacy land even harder by contrast.