Holmen (lit. 'The Islet') is a water-bound neighbourhood in Copenhagen, Denmark, occupying the former grounds of the Royal Naval Base and Dockyards. In spite of its name, deceptively in singular, Holmen is a congregation of small islands, forming a north-eastern extension of Christianshavn between Zealand and the northern tip of Amager.
Holmen was created by a series of land reclamations to house the Holmen Naval Base after it was moved from Gammelholm and used to occupy the entire area, but activities have gradually been moved elsewhere. Since the early 1990s, the area has instead been redeveloped for other use as a new district of the city, while the remaining naval facilities are confined to the northernmost islet of Nyholm. The area is today characterized by a mixture of residential developments, creative businesses and educational institutions and remaining military activities. Holmen is also home to the Copenhagen Opera House which was completed in 2005.
Though technically a part of the central Indre By district of Copenhagen, being a cul-de-sac as districts go, the area has a somewhat quiet and "remote" reputation and feel to it.