Screech, a bald eagle, is the official mascot of the Nationals. He made his first appearance on April 17, 2005, hatching out of an egg at RFK Stadium. The original Screech was designed by a local fourth grade student, but the bird has since taken on a new look, unveiling his new digs in 2009, featuring a slimmer profile to appear younger. The Nationals are one of several teams to have a make-your-own mascot store in their stadium, where fans can dress Screech however they want.

The Nationals are also supported by The Racing Presidents, comprise of George Washington, Thomas Jefferson, Abraham Lincoln, and Theodore Roosevelt. The four former world leaders race around the stadium, similar to the sausage races hosted by the Milwaukee Brewers.