Willis is the primary antagonist from the "I Know What You Did Last Summer" movie. He is portrayed by Muse Watson in "I Know What You Did Last Summer" and "I Still Know What You Did Last Summer", and by Don Shanks in "I'll Always Know What You Did Last Summer".
He is a widower that lives with his only son, working as a fisherman.
One summer, he was walking home when four teenagers, Julie James, Helen Shivers, Ray Bronson, and Barry Cox run him over. Believing him to be dead, they refused to call the police or try to help him and instead decided to drop his body in the ocean and not tell anybody.
However, he wasn't dead, just incapacitated. Thus, the next summer, he decided to stalk the teenagers who left him for dead. He kills local teenager Max Neurick before threatening and driving paranoia between the four friends. While at the croacker queen pageant, He kills Barry and later targets Helen. He murders the officer who was escorting Helen home however she escapes to her sister's store. He enters the store and murders Helen's older sister Elsa before pursuing Helen. He traps her in the second floor but she escapes yet again this time by jumping out the window. While Helen flees through the back alleyways Ben travels through the parade and manages to kill Helen after a brief struggle before she can get to the parade. Julie eventually discovered that Ben had in fact murdered David Egan, who they originally thought was the person they hit. Ben's daughter, Susie Willis, was killed in a car crash that David managed to survive. Blaming David, Ben went and killed him. After the murder, he was on his way home when the teens hit him. After killing Helen, He finds Ray running after Julie, who believes he is the fisherman. To gain Julie's trust, he knocks out Ray and then takes her on his boat. It is here where he reveals himself and attacks Julie. He succeeds in cornering her but Ray arrives and struggles with him. They eventually get the upper hand and cause Ben's hand to become tangled in some rope, where it then severed and Ben is thrown off the boat and into the ocean. Ben's body was never recovered and it is implied that he may still be alive. Julie and Ray were the only ones to survive the killing spree.
In "I Still Know What You Did Last Summer", it is confirmed that Ben survived his confrontation with Julie and Ray. He arranges for Julie to win a vacation to the Bahamas, where he would eventually make his way to her. For that, he is helped by his son Will Benson, who infiltrated Julie's group of friends and gained their trust. Ben arrives on the island and begins killing off the hotel staff. After a long chase, Ben confronts Julie in a cemetery on the island, where he prepares to kill her. Ray eventually shows up and gets into a struggle with Will. In the end, Benson is accidentally killed when Ray dodges an attack from Ben, and Ben's hook stabs him in the chest, which angers Ben further. In a rage, he attempts to kill Ray, but Julie shoots him multiple times in the chest, presumably killing him for good. One night however Ben is revealed to still be alive when he drags Julie under her bed apparently killing her.
In "I'll Always Know What You Did Last Summer", somehow he comes back to life and goes on another killing spree. At the end of the movie, he is impaled through the head and thrown into a thresher. He still survives this and shown behind Amber Williams and kills her just as she is heard screaming and hook noises are also heard. In the 3rd movie, there is a goof, it looked like Ben got a new hand, but he didn't, was still one-handed and has a hook for a hand.