Origin
Theodore Pendleton, A.K.A. Stone-Tough, was one of many heroes who joined the Anti-Registration Underground. It is unknown as to whether or not he was arrested by S.H.I.E.L.D. when they discovered the location of the Underground.
Creation
Stone-Tough was created by Paul Jenkins and Ramon Bachs, with his first (and only) appearance being in Civil War: Front Line #4 – Embedded, Part 4.