Axon Monster
Axos was a villain in Doctor Who. It was a composite creature, a scavenger entity which came to Earth, supposedly for fuel. Its real motivations were to drain all energy from Earth, with an ultimate plan to gain the secret of time travel, allowing it to feast anywhere in space and time. It teamed up with the Master who promised to lead it to Earth if Axos destroys the Doctor for him. Because the Master didn't tell Axos that the Doctor was also a Time-Lord, it traps the master and takes his Tardis, but he convinces it to let him go. The Master then teams up with the Doctor who tells Axos that he would allow Axos to consume his Tardis if Axos destroys the Time-Lords, but actually, the Doctor plans to trap Axos in a time-loop. However the Master reveals the Doctor's plan and escapes with his Tardis. Axos tries to assimilate the Doctor, but he manages to escape with his Tardis, leaving Axos alone in the time-loop. After its defeat, Axos returned to attack Earth twice.