Frank, as he likes to be called, is a cloned replica of the original Frankenstein Monster. He has become a part of the SHIELD team known as the Howling Commandos.
Frankenstein's Monster (Clone) was created by Keith Giffen and Eduardo Franisco and first appeared in Nick Fury's Howling Commandos issue 1 (2005).
Major Story Arcs
Frankenstein's Cloned Monster had become a part of the monster unit known as the Howling Commandos. He was super strong, but was also very intelligent compared to his original counterpart. "Frank", as he monster would like to be called, joined the team on a number of missions and even fought Merlin. The team eventually disbanned and Frank was not seen again.
More recently, a new monster-team of Howling Commandos was assembeled, but Frank was not a part of the line-up.