Nagin (1976)

A male and a female in their human forms are in love with each other. When the male turns back into a snake, he is shot by a member of a hunting party, who thought the snake was going to attack the woman. Enraged at the brutal killing of her beloved; the female snake begins to take revenge on the six involved, killing them one by one after assuming the form of a human.

Unfortunately the movie Nagin is not yet available on HBO Max.