Frederick Charles Krueger was a very disturbed man. He is the featured as the primary Antagonist in A Nightmare on Elm Street: Insomniac's Cut , played in this photo by amazing actor, Julian Richings .
A lot to Freddy is going to be left a mystery, as he is newly created for the Insomniac's Cut RPG.
One early, somewhat too sickening take on the charatcer can be found here: Nightmare_Fiend
Below remains the only known photo of him to ever exist.