Actor: Stephen Amell, Ref: Arrow

Concept

Powered Ex-Thief/Criminal Trying to Atone

Tropes

Did time in prison for crimez.
Got his life together, found love, got engaged, baby on the way and all that nice stuffz.
Elements of his past life came looking for (or caught up with) him, stuff happened and fiancee was murdered by Bad Guys™. The murder was never resolved due to crooked/negligent cops and some even suggested Jax may have done it himself.
Slipped into depression, drugs, alcohol, bad stuff....Hit rock bottom.
During a particularly bad trip, possibly on some new street drug, he went into a deep, dark, murder rage and killed Bad Guys associated with his wife's murder. This rage activated his latent powers.
With new abilities, he pull himself out of the hole his life had become and turned vigilante. He vowed clean up the cancer which had taken hold in his city and promised to protect those people of his neighbourhood from it.