V'Ger is a massive machine
entity that appeared in Star Trek: The Motion Picture
In 2271, V'Ger entered Federation space on its way to Earth to find the "Creator" and indexed everything it encountered in its memory banks before destroying it. The entity generated a power field cloud around it over 22 AUs in diameter and using the power in this cloud it could destroy any object it came across. V'Ger viewed organic life forms as carbon-based units "infesting" machines such as starships or even planets.
V'Ger became sentient after an unknown machine based alien race stumbled upon Voyager 6 and repaired it. This machine based entity could not believe that non-machines such as humans could have created Voyager 6 since it considered them inferior life forms. Upon reaching Earth and finding that humans were actually its creators, V'Ger joined with Starfleet Lieutenant Ilia and Commander Will Decker in order to better itself and evolved into a higher life form.
The name V'Ger was a corruption of Voyager 6. When the aliens found the probe the only letters visible were V, G, E, and R, hence V'Ger. Gene Roddenberry speculated around the beginning of Star Trek: The Next Generation that the machine race Voyager 6 was refitted by was the Borg.
Star Trek: The Motion Picture