The Space Unit is an organisation of hobbists devoted to the collection and study of covers and stamps issued on space themes. It has a world wide membership and is the largest independent astrophilatelic society in the world.

The Space Unit was founded in November, 1957 by a group of collectors in the Greater Chicagoland area and midwestern United States. It is incorporated as a non-profit organization in the State of Illinois. Since its inception, it has grown in membership into the largest astrophilatelic independent society in the world. Members are represented throughout the United States and Canada, as well as the five continents.The Space Unit is affiliated with the American Philatelic Society and the American Topical Association.