The Giant Borg is an object that appears in the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics. It was an immense battle suit crafted by unknown aliens in another dimension.
Night of 1,000 Sonics!
Both Robotnik and Robo-Robotnik v1.0 sought after the robot in order to dominate the Multiverse. With the help of Evil Sonic, Robo-Robotnik got the Giant's Hand (presumably the Giant Borg's inactive state). Once he activated it, it transformed into the Giant Borg around him. With his new weapon, he set out on a rampage of Mobius Prime, only to be defeated by an army of Sonics from across the multiverse. The robot fell apart into jigsaw pieces. Realizing how easy it would be to put back together, Sonic Prime gave each Sonic a piece of it to take back to their home dimensions so it would never be reassembled.
Years later by his universe's time, Robo-Robotnik (now reduced to a programmed consciousness on a derelict space station) found himself discussing his current predicament with Dr. Robotnik, the latter having been accidentally transported there by his rogue creation E.V.E.. When he returned him to Mobius Prime, Robo-Robotnik secretly stole location of the Giant Borg piece in his own dimension from Robotnik's memory. Now aware of its location, Robo-Robotnik managed to acquire the Giant Borg piece and construct a new robotic body for himself, ending his restriction to the space station.
A Tale of Two Hedgehogs
Not long after this, Robo-Robotnik recruited Evil Sonic to help him recover the remaining scattered components of the Giant Borg, only for Evil Sonic to mistake the Dr. Robotnik of the Sonic Underground universe for him. The Underground version of Robotnik re-assembled the Giant Borg and piloted it in an attack on his citizens, only for Sonic Prime and that zone's Sonic to destroy it by luring one of the suit's own missiles back towards it.