Club Unión Collado Villalba is a Spanish football club based in Collado Villalba, in the autonomous community of Madrid.

[1] Founded in 1960, it plays in Tercera Federación – Group 7, holding home games at Ciudad Deportiva de Collado Villalba, which has a capacity of 1,000 spectators.

In 1975, they merge with another club of the city to form Unión Deportiva Collado Villalba, renamed in 1992 as Club Unión Collado Villalba.

On 30 May 2023, the club became the reserve team of CF Rayo Majadahonda, replacing CD Paracuellos Antamira.

[2] On 1 July 2024, Collado Villalba became the second reserve team of Atlético Madrid after a ten-year agreement was reached; for the 2025–26 season onwards, the club will be fully incorporated into Atleti's structure and will be replaced by Atlético Madrid C.[3]