Thundercracker was one of the original Decepticon Seekers that first appeared in the original Transformers cartoon. Thundercracker had very few major roles in the original cartoon but was usually portrayed as someone who disliked Starscream and would go out of his way to get the fellow seeker in trouble. In the movie he was one of the Decepticons who was thrown out of Astrotrain and reformatted by Unicron.
In Cybertron, Thundercracker was a blood thirsty warrior but like many others in the show changed allegiance multiple times. Finally, in Animated, Thundercracker was one of the Starscream clones. Each clone was given a particular personality trait from Starscream and Thundercracker became an egomaniac thanks to this. His role in animated was very limited as he was basically lost in space for a majority of the series.