Little is known of the Tick's past. What is known, however, is that he was interred in an insane asylum while already costumed as the big blue hero. He grows bored of his confinement and heeds destiny's call to do something more. He breaks out to be a superhero.
The Tick is nigh-invulnerable, which makes him able to withstand intense trauma. This does not keep him from feeling pain. Crashing into the ground or having a bullet shot into his teeth won't break his body, but he will still feel the discomfort of it all.
He also has a "drama power," which gives him the ability to make any situation more dramatic by his mere presence.
The Tick probably has super strength. And if it is not super then it is certainly impressive.
Though not necessarily a power, The Tick's battle-cry is said to baffle, or stun, his opponents. Before battle, he yells out, "SPOON!"