In a Jewish bar mitzvah service, the person who oversees the Torah reading and calls people for aliyot is a gabbai.
A gabbai helps coordinate the practical details of a synagogue service. Duties can include announcing who is called to the Torah, assisting with the scroll, directing the reader, and managing the order of honors. In many congregations, more than one gabbai shares these responsibilities.
The role is especially visible during a bar or bat mitzvah because the student’s Torah honors require careful scheduling and preparation. The gabbai may also help correct or support the reader without replacing the student’s public participation.
A gabbai is not the same as the maftir. Maftir refers to the final Torah honor or its recipient, while gabbai describes the service official coordinating the reading. A mohel performs circumcision, and a dayan is a religious judge.