OC- Midgard And Fenris Picture

Right. First off, if anyone can tell me where these names are from, they get a cookie.
(For you hopeless people, you can either look it up on Wikipedia, or realize that I adore mythology. )
And for you mythology geeks that can't quite remember the name, the appearance should be a dead giveaway.

Anywho, these are part of my "bad guy" gang in my plot.
The main setting is the "Other Realm", underworld, whatever you want to call it.