Jazz

Jazz is one cool cat. You would be too if you were a robot that transformed into a Martini Porsche. As right-hand bot to Optimus Prime, Jazz leads the Special Operations division, and has his own team of agents that are at his disposal. However, he often sends himself on the most taxing of missions. This is out of a combination of sensability (he has the coolest head when the missions get hot) and the latent need to protect others that causes him to want to put himself in danger before others. Jazz is aptly named, too. Like the musical style that adapts to the players, he too can adapt to any situation, any culture, any problem. This makes him an invaluable commander on tough missions, and this is why he is indispensible to Optimus Prime.
 

IDW Continuity

On Earth

Jazz was a member of the Autobot infiltration unit dispatched to Earth to combat the Decepticons' agenda on that world. In this unit, he served as Prowl's second in command. His specialty was that of a Special Ops soldier and commander, having a long resume of assignments that were mostly top secret. At first, the assignment on Earth was a quiet one with the Autobots unable to locate the Deceptions' main base. A lucky break came when humans discovered its location, and things began to escale from there. Optimus Prime arrived on Earth and took personal command of the unit, making Prowl now the second in command rather than Jazz.
 

When Sunstreaker was ambushed and seemingly destroyed by humans, Jazz took Wheeljack to recover the remains from an impound yard, hoping to acquire them before the human public discovered Sunstreaker was more than just a car. There, they encountered humans from the same organization responsible for the attack now attempting to steal the remains. Jazz and Sunstreaker attempted to stop them but were temporarily disabled by weapons specifically designed against them. Optimus Prime was able to stop the humans' escape.
 
The conflict with the Decepticons on Earth escalated to the point of open confrontation in the former Soviet state of Brasnya and only got worse from there. Megatron brought the destructive Sixshot to Earth. Sixshot attacked Ark-19 as Jazz and the other Autobots were relocating it to the Gulf of Mexico. The ship crashed, and the Autobots were forced into direct battle with Sixshot. During this battle, Sixshot ripped off Jazz's right arm and took him out of the fight.

Later, a traitor in the Autobot ranks inadvertently aided the Decepticons in luring the Autobots into an ambush. Jazz and his fellow Autobots were overwhelmed and forced to surrendered. However, the Decepticons had no intent of showing mercy on them. They were instead to be executed in a unique fashion by being teleported through a space bridge to their desolated homeworld of Cybertron and fed to the Swarm of Insecticon drones ravaging that planet. Optimus Prime, the last Autobot to be sent through the space bridge, was able to fight back and prevent the Decepticons from fully carrying out this execution. This act left him nearly dead, and the Autobots were now stranded on Cybertron. While Prowl was technically Optimus Prime's second in command, Jazz assumed leadership of the unit as protocol required he do in certain situations.

All Hail Megatron

Jazz did all he could to keep his unit together in these tough circumstances. After establishing a bunker where they could ideally avoid contact with the Swarm, he routinely sent out recon teams in search of energon or any other potential resource left on their barren world. Every time, the teams came back empty-handed. It was frustrating, but he did not honestly ever expect them to find anything. Keeping them occupied was the main purpose of the missions. And while the whole unit was aware of Optimus Prime's state of near-death, Jazz chose not to tell them that Megatron had also taken the Matrix from Prime. The only other Autobots who knew of this were Prowl and Ratchet. Their present situation and the knowledge of a traitor being among them was already enough to push the unit's stress level above the boiling point.
 

After almost a year on Cybertron, another Autobot unit arrived. It was Kup's unit, which had been shot down in their Ark by the Decepticons. With tensions as high as they were, there was an immediate clash of leadership between Jazz and Kup. Kup purposely pushed Jazz's buttons upon arrival and taunted him to do something, with Springer warning Jazz off of doing so. Jazz struck down both Spring and Blurr and had his blaster aimed at Kup's head before anyone else could react.
 
The two leaders talked it out later. Kup wanted Jazz as his second in command, but Jazz did not think much of the sort of reckless Autobots Kup used as his little soldiers. But recognizing that this was not the kind of situation to argue, Jazz fell in line with the chain of command. The Autobots relocated to a more secure bunker with the Swarm right behind them, threatening to overwhelm them sooner or later. Optimus Prime then came back online in time to help bolster their forces and fight off the invading Swarm. The arrival of Omega Supreme not only turned the tide of battle, but it gave the Autobots a way back to Earth.
 

Jazz and the rest of the Autobots dropped from the sky over the island of Manhattan, where the Decepticons were already waging a war against the humans. The battle went in the Autobots favor, and the Decepticons retreated with a badly damaged Megatron.