Impactor died fighting during the Great War along with his fellow Wreckers. His name was mentioned by Wheeljack in his conversation with Bulkhead.
In the Rage of the Dinobots comic, he is heard leading a small group of Autobot ships leaving Cybertron. It is likely that this occurred before he perished, or possible that he survived and was only thought to be dead.
Despite only being mentioned in the series once, Impactor received a toy during an accompanying Transformers toyline at the same time of Transformers Prime's airing.