The Memorial Union, also locally known as "the Union" or "the Terrace", is located on the shore of Lake Mendota on the campus of the University of Wisconsin-Madison in Madison, Wisconsin.

The exterior was designed by University Architect Arthur Peabody. It opened in 1928, and is run by the Wisconsin Union, a membership organization. Porter Butts, the first director, called it a "college union" because it combines the characteristics of a student union ("student activity center" in other countries) and a student government ("students' union" in other countries) in an organization that brings together students, faculty, and members of the surrounding community. It has gained a reputation as both one of the most beautiful and domineering student centers on a university campus. Outside the main building is the Memorial Union Terrace, a stone outdoor dining and recreation area on the shore of Lake Mendota. The Terrace was designed by Peabody's daughter Charlotte. It is a popular spot for socializing among students and approved visitors, with the backdrop of the beautiful lake, sailboats in view, and with the sound of live music, usually free to the public (paid by student fees), in the evening.

The Union is also known for der Rathskeller , a German pub in the Union that directly connects to the Terrace outside. As of 2007, a new placard at the entrance to the Rathskellar advises that the building is private and anyone can be asked to leave unless they can show proper ID. Political debates and backgammon games are common among students over a beer on the terrace.