What is the name of the Enterprise's chief engineer?

The Enterprise's chief engineer is Montgomery Scott, better known as Scotty. He served aboard the USS Enterprise under Captain James T. Kirk in Star Trek: The Original Series.

Scotty was played by Scottish-Canadian actor James Doohan. The character became famous for keeping the Enterprise operating under extreme pressure, often while making urgent repairs or finding a way to exceed the ship's stated technical limits. His repeated report that he was giving the engines “all she's got” became one of the show's most recognizable motifs.

Scotty's full name is Montgomery Christopher Scott. He was a Starfleet officer and a highly experienced engineer, not the ship's captain or science officer. Christine Chapel was a nurse, Pavel Chekov served as navigator, and Hikaru Sulu was a helmsman and later captain. Those roles are common sources of mix-ups because all four were prominent Enterprise crew members.

Scotty also appeared in the first seven Star Trek feature films. In Star Trek III: The Search for Spock, he transferred technical knowledge to the USS Excelsior's computer in a scene that helped preserve his reputation as an ingenious engineer.