Barrier-bots

The Barrier Bots guard the entrance to the Near Death Star. In A Clone of My Own, they only let Fry in, thinking him to be Professor Farnsworth, when he provides them with a tissue sample (courtesy of Cubert), and impersonates an old man. Later on, when Fry, Leela, Bender, and Cubert escape the Sunset Squad Chasers, they break off the arm of one of the Barrier Bots.

Quotes
Fry: Uh ... I-I've got talking hump syndrome. Barrier Bot 1: Ah, T.H.S.
 * Fry: What? I'm old! Listen. [Impersonating Farnsworth.] Hey, you kids! Get off the lawn! Barrier Bot 1: Hm. It is true that old people are often concerned with children on their lawn. Barrier Bot 2: There's no denying that.
 * Barrier Bot 1: Did your hump just say something?