Jim Hopper’s nickname in “Stranger Things” is “Hop.” James “Jim” Hopper Jr. is the police chief of Hawkins, Indiana, and the shortened form of his surname is used by people who know him well.
Hopper is played by David Harbour and first appears in the series premiere, “Chapter One: The Vanishing of Will Byers,” which aired in 2016. His role expands from investigating Will’s disappearance to protecting Eleven and confronting threats from the Upside Down.
“Hop” is easy to confuse with “Chief,” since Hopper is frequently called “Chief” by Hawkins residents and police officers. “Chief-O” is also listed among his nicknames, but it is not the ordinary shortened name used in the question. “Jim” is his given-name nickname, while “Hop” comes from Hopper.
Hopper’s character is also a Vietnam veteran and a former New York City homicide detective. His grief over the death of his daughter, Sara, shapes much of his early behavior, while his relationship with Eleven and Joyce Byers becomes central to the story.