Rayo Vallecano

Rayo Vallecano was founded on 29 May 1924 in the hometown of Prudencia Priego, wife of the club's first president Julián Huerta. Greatly inspired by River Plate (a Football club from Argentina), in 1949, after an agreement with Atlético Madrid, a red diagonal stripe was added to the team's kit, and the club reached Tercera División for the first time in its history.

One of the perennial yo-yo clubs of Spanish football, and always in the shadow of the two biggest clubs in the city (Real Madrid and Atlético Madrid), Rayo Vallecano spent many years during the 1980s and 1990s moving back and forth between La Liga and Segunda División. The 1983–84 season was the worst during the 1980s. The club finished in the last position in Segunda División and was relegated to Segunda División B.

Due to a tragedy Rayo Vallecano turned out to be Laurie Cunningham's last club; he was killed in a car crash just outside Madrid in 1989, after a sole season. He had recently won an F.A. Cup winners medal with Wimbledon F.C. in England the previous year and had also represented neighbours Real Madrid for four years.

They appeared to have consolidated their top flight status after gaining promotion in 1999, and the team's most successful season came in 2000–01 when they reached the quarter-finals of the UEFA Cup, going out only to eventual runners-up Alavés; Rayo finished ninth in the previous campaign, but entered the competition via the fair play draw.

However, the club shortly thereafter fell on hard times, enduring successive relegations in 2003 and 2004. For 2005–06 manager Míchel, a Real Madrid legend in the 1980s and '90s, was hired.

Rayo finished the 2006–07 season in second place in Segunda División B, winning the promotion play-off semifinal but losing in the final to Eibar (1–2 aggregate). The following campaign, the team returned to division two after a four-year absence after a victorious run in the playoffs, disposing of Benidorm in the semi-final and Zamora in the last game 2–1 on aggregate.

In its first seasons back in the second tier of Spanish football, Rayo finished comfortably, often either in or just outside the promotion places. In 2010–11, the team ranked in second position and returned to the top flight after an eight-year absence, only trailing champions Real Betis in spite of very serious economic problems.

In March 2014, Huawei agreed to sponsor Rayo Vallecano for two league matches against Real Madrid and Athletic Bilbao.

In August 2015, Rayo Vallecano purchased the majority of Oklahoma City FC, a NASL expansion franchise which had yet to officially play a game renaming the club to Rayo OKC, despite the stadium increasingly needing work. It was the first ever entry of a Spanish club into the American sports market and mirrored a 2013 sponsorship agreement with Qbao in terms of expanding the club's profile overseas. Rayo OKC folded after a year due to Rayo Vallecano's relegation from La Liga and a dispute between the co-owners led to less finance for the U.S. side.

In May 2016, Rayo Vallecano were relegated to the Segunda División, finishing 18th in the 2015–16 La Liga season. This ended their five-year streak in La Liga, their longest ever stay in the top-flight. Their first season back in the second division was a poor one, with both problems on the field and off, and they finished in 12th position. Rayo went through three managers in the 2016–17 Segunda División season before finally settling on club legend Míchel. He revived the club from the relegation places to 12th, almost making the playoffs.

At the start of the 2017–18 Segunda División season, the club appointed their recently retired goalkeeper David Cobeño as the sporting director of the club. They secured their promotion with a 1–0 over CD Lugo with one game remaining. That season the club won Segunda División with 76 points in 42 games.

On 20 March 2019, the club appointed Paco Jémez as head coach, and on 4 May, Rayo was relegated back to the Segunda División after losing 4–1 to Levante UD, eventually finishing last.

In August 2020, the club appointed Andoni Iraola as head coach. They finished sixth and won promotion in the playoffs against Girona FC; despite losing the first leg at home 1–2, the team came back to win the second leg 2–0 away to claim a place in La Liga for 2021–22. In February 2022, Iraola's side defeated RCD Mallorca to make the semi-finals of the Copa del Rey; it was the second time in club history and first since 1982. The club finished 12th in La Liga. This was a big achievement as they were by far the league's smallest team, and most had predicted that they would be relegated.