Okay, so, aside from some terrifying skin variations on the models (Pinocchio human, Legion Eredar, Worgen from your deepest nightmares…) this is called the Frosty. The reason should be obvious. My death knight that wears this transmog is a blood elf with blue skin and hair, so of course it works nicely. I did include Pandaren, even though they cannot be death knights. But there are non-DK alternatives!
Shoulders: Necrotic Boneplate Pauldrons (DK only! For non-DK shoulders use Backbreaker Spaulders
Chest: Ornate Mithril Breastplate (This one and the legs are tough because the patterns are no longer in-game. You’ll have to trawl the AH or find someone with the pattern to make them for you!)
Waist: Hidden (Pre 7.1 I used Acherus Knight’s Girdle, but it leaves an odd ring around the character’s waist.)
Legs: Ornate Mithril Pants (See text on chest)
Feet: Boots of the Underdweller
Wrist: Just don’t let it poke over your gloves.
Gloves: Wild Combatant’s Dreadplate Gauntlets
Weapon: Basic Frost artifact or Hailstorm, for a Two-Hand alternative I’m a fan of Demise or Shadow’s Edge