In his prime, The Terror was a force to be reckoned with, but he's so old he's not able to pose much of a threat anymore.
The Terror vs. The TickEdit
He's Barry's old nemesis. Barry tricks him into thinking that he's changed his costume to blue and has a new sidekick, so The Terror now thinks that The Tick is his old nemesis.
The Terror supposedly met his end in a mountain chalet, where he and the rest of The Evileers were trying to destroy the Tick and his supergroup, but the Man-Eating Cow found them and devoured them.
However, The Terror appears in later comics, so he apparently survived the attack.