Oceanographers have been left baffled as to how the crab, which usually inhabit the icy Bering Sea off the coastline of Alaska, got 4,700 miles from its normal habitat.
The crab was discovered on the beach in Redcar, north Yorkshire by oceanographer David McCreadie and his fiancee Diane Weinoski.
The formidable-looking crustacean was around 30 inches across, although the crabs can grow to have a leg span of up to five feet.
It suggests the crab was still relatively young and may have been swept to the UK by powerful currents or in a storm.
Red king crabs were first introduced to the Barents Sea off northern Russia in the 1960s but have now become so numerous they have overflowed down the west coast of Norway.
Some fisherman fear these massive crabs...