Bumblebee/Goldbug

Transformation: Volkswagen Beetle

Of all of the Autobot's, Bumblebee was the closest with Optimus Prime, and also forced strong friendships with Spike & Carly Witwicky, as well as Chip Chase.  Bumblebee's other accomplishments included, Planting a bomb in the Ruby Mines of Burma, Locating, then leading the Autobot's to the first Decepticon Space Bridge (though this only happened after being brainwashed by Megatron and leading the Autobot's into a trap),  Leading the out of control Grimlock away from Teletran -1 so that Ratchet could begin repairs on it, Finding Dinobot Island (With Powerglide), and the list goes on and on.

In the year 2005, Bumblebee along with Spike Witwicky was placed in charge of one of the Autobot moon bases (Moon Base 2), during the attempt to take back Cybertron from the Decepticon's.  Unfortunately, at that time the Super Transformer, Unicron, came to Cybertron to devoured both of the Moon Bases.   After seeing Jazz and Cliffjumper being sucked into Unicron, Spike and Bumblebee attempted to destroy the monster by blowing up the moon as he ate it.  This plan though a brilliant idea, did not even scratch Unicron and they shared the same fate as Jazz and Cliffjumper.  Luckily, Spike's son Daniel (who had entered Unicron with another group of Autobot's that had crashed their ship right through one of his eyes) found them just minutes before they were to be dropped into a giant vat of acid, and saved them.

Bumblebee was then sent to Earth to help man Autobot City, and was one of the Autobot's that tried to stop the new Decepticon City Tripticon from destroying the Ark.  Though the most exiting thing to happen to Bumblebee since that day was probably when the Ghost of Starscream stole the eyes of Metroplex, he never imagined that his life would change forever when a Human named Jessica Morgan came to Autobot City with information that Optimus Primes body was on Earth.

Bumblebee was selected to keep a watch for Decepticon's (in case they got wind about Optimus Prime as well) with 3 other Autobot's.  Though they failed to keep the Decepticon's out of the lab, they did try to stop Superion (who was now infected with the Hate Plague), but was badly damaged in the attempt.  He was later recovered and rebuilt into a new body by the Quinteson that repaired Optimus Prime, and took on the new name of Goldbug.

Unfortunately, Goldbug was unable to help much in fighting the Hate Plague (he was infected on Charr), he retook his place by Optimus Primes side, and volunteered to go with him to Cybertron to stop the Decepticon's from opening the Plasma Energy Chamber and stayed behind when Optimus Prime went to Nebulos to find the missing Autobot's and recover the Key to the Plasma Energy Chamber.  Though not much is known about all the Autobot's that stayed behind that day, it is safe to assume that Goldbug was one of the Autobot's that had their power packs removed to power Galvatron's rocket engine.

Not many Autobot's over the last few million Earth years have proven themselves worthy of being called an Autobot hero, but in this case it is believed that Bumblebee/Goldbug has, in a human term, earned that right in spades.