Sheriff Frank Kelly is the head of the Kingston Falls police and is at the police station with his deputy, Brent, during the Christmas Eve when the gremlins rampage through town. He is a very serious man and doesn't take Billy Peltzer's words of warning regarding the Gremlins seriously. He was first seen at the start of the movie trying to get a Christmas tree for free.
After saving his mother Lynn Peltzer from a gremlin and leaving her with the neighbors, Billy goes to the police station and tries to talk to Frank and Brent about what the gremlins would do to the town, but they don't take him very seriously. After he shows them Gizmo to them they wonder how a furry creature like that can turn into many scaly little creatures. When Frank then receives a phone call about the Futtermans who have been in a strange snow plow accident, he goes away with Brent to check it out right after telling Billy to go home with Gizmo. As they are out in their police car, they witness the bizarre death of Ruby Deagle and then they see how a man in a Santa costume is attacked by some gremlins, whereupon they drive back to the police station, unaware that a gremlin has destroyed the brakes. Unfortunately, when a car pulls out in front of them, Frank can't stop the vehicles and he ends up crashing into some parked cars, whereupon their car flips over with them inside. It is unknown whether or not he and Brent died after this incident.
- Frank's surname comes from his police uniform's nametag.
- In George Gipe's novelization, his surname is "Reilly."