Christopher Van Hollen Jr. (born January 10, 1959) is an American attorney and politician serving as the senior United States senator from Maryland, a seat he has held since 2017. A member of the Democratic Party, he served as the U.S. representative for Maryland's 8th congressional district from 2003 to 2017 and as a Maryland state senator from 1995 to 2003.

In 2007, Van Hollen became the chair of the Democratic Congressional Campaign Committee (DCCC). In this post, he was responsible for leading efforts to defend vulnerable Democrats and get more Democrats elected to Congress in 2008, which he did. House Speaker Nancy Pelosi created a new leadership post, Assistant to the Speaker, in 2006 so that Van Hollen could be present at all leadership meetings. He was elected ranking member on the Budget Committee on November 17, 2010. Pelosi appointed Van Hollen to the 12-member bipartisan Committee on Deficit Reduction with a mandate for finding major budget reductions by late 2011. On October 17, 2013, Pelosi appointed Van Hollen to serve on the bicameral conference committee.

Van Hollen ran for the United States Senate in 2016 to replace retiring Senator Barbara Mikulski. He defeated U.S. Representative Donna Edwards in the Democratic primary and won the general election with 61% of the vote to Republican nominee Kathy Szeliga's 36%. He was reelected in 2022 with nearly 66% of the vote to Republican nominee Chris Chaffee's 34%. Van Hollen chaired the Democratic Senatorial Campaign Committee (DSCC) from 2017 to 2019. Van Hollen became Maryland's senior senator when Ben Cardin retired from the Senate in 2025.