What is the biggest vehicle in Halo?

M510 Mammoth M510 Mammoth - Heavy wheeled transport vehicle used by the UNSC. It is the largest known terrestrial armored fighting vehicle employed by the UNSC, dwarfing even the similar Elephant HRV in size.

Whats the original Halo called?

Halo: Combat Evolved Original trilogy. The games of the original Halo trilogy were developed by Bungie, and are first-person shooters in which the player experiences most action from the protagonists perspective. The first title in the series is Halo: Combat Evolved on Xbox, released on November 15, 2001.