| United Left of Castile and León | |
| Native Name: | Izquierda Unida de Castilla y León |
| Leader1 Title: | General Coordinator |
| Leader1 Name: | José Sarrión |
| Merger: | Communist Party of Castile–León Izquierda Abierta Communist Youth of Castile and León Republican Left Independents Party of Socialist Action (1986-2001) Progressive Federation (1986-1988) Carlist Party (1986-1987) Humanist Party (1986) |
| Headquarters: | C/ Panaderos Nº 29, 1º C. Valladolid |
| Membership Year: | 2015 |
| Membership: | 1,100 official members and 1,500 official sympathizers.[1] |
| Position: | Left-wing to far-left |
| National: | United Left |
| Affiliation1 Title: | Union affiliation |
| Affiliation1: | CCOO |
| Seats1 Title: | Town councillors |
| Seats1: | Not including those gained in coalitions |
| Website: | iucy.org |
| State: | Spain |
United Left of Castile and León (; IUCyL) is the Castilian-Leonese federation of the Spanish left wing political and social movement United Left. José María González[2] is the current General Coordinator. The major member of the coalition is the Communist Party of Castile–León (PCCL, Castilian-Leonese federation of the PCE).
In the Castile and León elections of 2015 IUCyL gained 1 seat in the Cortes of Castile and León.