The Evil Hand is an infamous Deadite and a minor antagonist in Evil Dead 2 - despite being a minor villain, it is one of the most remembered enemies in the Evil Dead franchise.
The Evil Hand is in reality the possessed limb of Ash (the main hero) - the result of Deadite torment - which turned his hand against the rest of his body and it continually tried to strangle and beat him until Ash was forced to literally cut his own hand off.
However this resulted in a gruesome (yet comical) scene in which the now "free" Evil Hand went on a rampage and taunted Ash further - even giving him the middle finger as he fought the possessed limb until eventually killing it.
Losing his hand would ultimately result in Ash gaining his now iconic chainsaw-hand which would become a major part of his character and the Evil Dead series as a whole.
The Evil Hand also appeared in many Evil Dead videogames including Evil Dead: Regeneration.