What is the person who leads an orchestra called?

The person who leads an orchestra in performance by standing in front of the group and conducting, with or without a baton, is called a conductor. The term "director" usually refers to a more administrative role, such as being in charge of what music is performed, etc. In most groups, the music director or artistic director is also the main conductor. Major professional orchestras often have guest conductors or assistant conductors.

Many people say "direct" instead of "conduct", but "conduct" is technically the proper term. In Britain, it is common to say the orchestra is "led by" someone rather than "conducted by" someone.

Some orchestras play without a conductor. In these cases, the concertmaster (principal violinist) often performs a leadership role in establishing the tempo at the beginning of a piece.