A variety of phrases as if being pronounced by a robot.
Fluttery high pitch ringing zaps
digital, melodic, robot style synth riff
Deep counting from one to eleven as if pronounced by a robot.
The word "warning" as if pronounced by a robot.
A single robotic footstep
A mid tone cutting in and out randomly and modulating in pitch.
2 quick modulations in zapping tone
Reverse chime - creepy alien or creature element.
Robotic beeping, R2D2 style.