Castilian Popular Unity

Castilian Popular Unity (Spanish: Unidad Popular Castellana, UPC) was a leftist nationalist political party active in the Spanish autonomous community of Castile and Leon.

UPC was founded in Valladolid in 1983 as Popular Unity-Revolutionary Unity, changing the name some months later.

The majority of its members were young leftists and ex-members of the Communist Movement.

UPC only had a stable presence in Castilla y León, specially in the provinces of Burgos, Valladolid and Segovia.

UPC had close ties to the Basque coalition Herri Batasuna.