The Stunticons were a gestalt team of Decepticon cars, added to the Transformers toy line in 1986. The team consisted of Drag Strip, Dead End, Wildrider, Breakdown, and their leader Motormaster. Together, the combined to form the super-robot Menasor.
The Stunticons were intended to add some "ground support" to Megatron's team, since the Decepticons were primarily jet-powered at this time. In the Transformers cartoon episode where they first appeared, "The Key to Vector Sigma", Megatron created them by stealing four cars and a truck from their human drivers and modifying them to transform into robots, then taking them to Cybertron to receive personalities from Vector Sigma. The Autobots followed, and responded by creating the Aerialbots to give them an advantage in the air.
The Stunticons were used fairly well in the cartoon from that point on, but not as often as their Aerialbot counterparts. They seemed to be gradually eclipsed by the Combaticons, which were introduced in the same year as toys and just a few episodes later in the cartoon.