- "It's not only prisoners who grow coarse and hardened from corporal punishment, but those as well who perpetrate the act or who are present to witness it."
- —Mark Scheffer[src]
Mark Scheffer, also known as Shrapnel, was a former toy shop owner and serial bomber. He terrorized Starling City and endangered the life of Sebastian Blood, before being stopped by The Arrow. He was later enlisted into the Suicide Squad by Amanda Waller but after disobeying orders, was killed by a bomb implanted in his head.
In "Blast Radius", he is seen as an anti-government serial bomber who follows a militia group and the group's M.O. is how he is identified by Team Arrow when they analyze the bomb remains given by Officer Quentin. He goes by the alias of Shrapnel but does not appear visually or physically as Shrapnel. After bombing two government buildings in Starling, Shrapnel targets Sebastian Blood's Unity Rally, he shoots Diggle and after a brief chase, The Arrow manages to catch him and he's arrested.
- Explosives Creation: Mark Scheffer has be shown to be an exceptional skilled explosives creator, making timed bombs, as well as explosives that blow in a specific way.
- Flashbangs: Scheffer uses highly sophisticated flashbangs to blind his enemies, even once attempted to use it on The Arrow.
- Smoke Grenades: Scheffer uses smoke pellets to escape his enemies, which was how he was able to escape The Arrow when they first crossed paths.
- Grenades: Scheffer also keeps regular based grenades as he attempted to kill innocent civilians with one at Sebastian Blood's Unity Rally.
- In the DC comics universe, Mark Scheffer is a supervillain by the name of Shrapnel. In the show, he uses "Shrapnel" simply as an online alias.