- "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 (died March 2014), also known as Shrapnel, was a former toy shop owner and psychotic serial bomber. He terrorized Starling City and endangered the life of Sebastian Blood, before being stopped by The Arrow. He was later drafted into the Suicide Squad by Amanda Waller, but after disobeying orders and trying to escape, he was killed by a bomb implanted in his head.
Scheffer is seen as an anti-government serial bomber, who follows a militia group. The group's M.O. is how he is identified by Team Arrow, when they analyze the bomb remains given by Officer Quentin Lance. 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, shoots Diggle and after a brief chase, The Arrow manages to catch him, and sever the activation button for his devices. Subsequently, he is arrested.
Mark was a complete psychopath who believed that all government was corrupt. However, hypocritically he had a complete disregard for innocent lives, which he put in danger. He was also very arrogant: when A.R.G.U.S. recruited him for Task Force X, he believed that they would just release him from prison without having him on a leash, leading him to attempt to abandon Task Force X; this attempt led to his deserve death by the immoral Amanda Waller.
- Explosives: Mark was shown to be an exceptionally skilled explosives creator, making timed bombs, as well as explosives that blow in a specific way. He also knew how to use cellular technology to control his bombs.
- Computing Skills: His skills with cellular technology allowed him to keep Felicity from tracking him, tricking her with another signal to follow while he escaped.
- Skilled marksman: Mark was shown to be skilled in the use of firearms.
- Skilled driver: Mark was skilled in driving his van without accidents, allowing him to easily escape The Arrow with the combined usage of evasive driving, a smoke grenade, and fool Felicity by having her track a different signal than his.
- Flashbangs: Mark used highly sophisticated flashbangs to blind his enemies, even once attempted to use it on The Arrow.
- Smoke Grenades: Mark used smoke pellets to escape his enemies, which was how he was able to escape The Arrow when they first crossed paths.
- Grenades: Mark also kept regular based grenades as he attempted to kill innocent civilians with one at Sebastian Blood's Unity Rally.
- Gun: Mark was proficient in using a gun and used a gun to threaten and shoot John.
- In the DC comics universe, Mark Scheffer is a supervillain by the name of Shrapnel, a being of organic metal who can explode and reconstitute his body at will. In the show, he uses "Shrapnel" simply as an online alias.
- This version of Shrapnel is very similar to the Batman Beyond character Mad Stan. Like Stan, Scheffer is a nonconformist radical psycopath who shows a hatred for "the System", believing it to be corrupt. They also share a liking for explosives.