Rayo Vallecano de Madrid, S.A.D. - often known as Rayo Vallecano or even simply Rayo ("thunderbolt" in Spanish) - is a professional football club based in the Vallecas neighbourhood of Madrid and currently competing in Spain's top league, La Liga. They play their home games at Campo de Fútbol de Vallecas.
Founded in 1924, the club had spent many years being a typically "yo-yo club" going between promotion to La Liga to relegation to Segunda División in the 1990s and 1980s; and even at one point being relegated to the Segunda División B. In recent years, this pattern has immerged again having last been in the second division in 2020-21. Some of the club's biggest achievements are making the quarterfinals in the 2000-01 UEFA Cup and making the semifinals of the 2022 Copa del Rey.