Sominus microcephalus, also known as: the Greenland shark, sleeper shark, gurry shark, grey shark, or Eqalussuaq (Inuit).
They live farther north than any other shark, in the depths of the freezing ocean. They're incredibly sluggish and mostly blind.
They are comparable in size to a Great White.
Now the exciting parts:
The sharks are so sluggish that they can be pulled from the water by hand (with the help of a pulley system of course...they're big). They don't even appear to struggle when they come out of the water. Despite how slow they seem, their stomachs have been found to contain fish, squid, seals, reindeer, horses, and polar bear.
Their flesh is toxic, but they can (and occasionally do) cannibalize each other. The flesh can be prepared so that it is no longer toxic, and is considered a delecacy in Iceland and Greenland. If the toxic flesh is eaten it can produce effects similar to extreme drunkenness.
The sharks have a symbiotic relationship with a parasitic copepod, Ommatokoita elongata. This creature attaches to the cornea of the shark and causes scarring there, leading to their partial blindness. The benefit to the shark is unknown, though it is hypothesized that the copepod acts as a fishing lure.
Greenland sharks have been spotted snatching reindeer from the water's edge in Canada.