Dean of the United States Senate
The dean of the United States Senate is an informal term for the United [States Senate|senator] with the longest continuous service, regardless of party affiliation. This is not an official position within the Senate, although customarily the longest-serving member of the majority party serves as President [pro tempore of the United States Senate|president pro tempore].
The dean as of 2025 is Republican [Party (United States)|Republican] senator Chuck Grassley of Iowa. He has been in the Senate since 1981 and became dean in 2023 with the retirement of Patrick Leahy.