In WALL-E, the small cockroach that becomes the robot's companion is named Hal.
Hal lives among the abandoned waste of Earth and follows WALL-E during his daily routines. WALL-E is a waste-collecting robot left behind after humanity evacuates the polluted planet, and Hal is one of the few living creatures shown surviving there. The insect's name is a playful reference to HAL 9000 from 2001: A Space Odyssey, another famous science-fiction film involving artificial intelligence.
Hal does not speak, but its movements and reactions establish it as WALL-E's friend. The companionship also helps show that WALL-E has developed curiosity and emotional attachment despite being designed for repetitive industrial work.
Viewers sometimes answer M-O, but M-O is a separate cleaning robot encountered later aboard the Axiom. Hal is the living cockroach from the opening Earth sequences.