Emanuel Celler was an American Democratic politician from New York who represented parts of the New York City boroughs of Brooklyn and Queens in the United States House of Representatives for nearly 50 years, from March 1923 to January 1973. He served as the dean of the United States House of Representatives from 1965 to 1973. Celler chaired the House Committee on the Judiciary for eleven terms between 1949 and 1973 and was a leading advocate for the liberalization of immigration and naturalization laws, from his early stand against the Immigration Act of 1924 to his sponsorship of the Immigration and Nationality Act of 1965. He ranks as the fifth longest-serving congressman in history and the longest-serving member of either house of Congress in New York's history.

The dean of the United States House of Representatives is the longest continuously serving member of the House. The current dean is Hal Rogers, a Republican from Kentucky, who has served in the House since 1981. The dean is a symbolic post whose only customary duty is to swear in a speaker of the House after they are elected. This responsibility was first recorded in 1819 but has not been observed continuously – at times, the speaker-elect was the current dean or the speaker-elect preferred to be sworn in by a member of their own party when the dean belonged to another party. The dean comes forward on the House Floor to administer the oath to the speaker-elect, before the new speaker then administers the oath to the other members.