Death is the boss of chapter 10 in Magicka. He is also apparently the owner of a travel agency-this is a reference to "Grim Fandango".
Death is immune to most spells, except those that include life. He has several attacks.
Death is able to summon skeletons to aid him, he can surround you with illusions of himself, but most importantly, he is able to ONE-SHOT anything in the entire game, so evading his attacks with teleport or interrupting them with life is important.
After he's defeated, Death let's you summon him as a spell. As a spell, Death still one-shot kills any creature, and chases the one closest to dying (with the least % of health). It has been known that if properly positioned, Death can instantly kill bosses, such as Fafnir.
Death deals damage based on how much health a target is missing, unlike Vortex that instantly tears apart a portion of the screen, dealing infinite damage.