Two-time La Liga winner with Real Madrid, Luis Olaso started out at Atletico Madrid and made 13 appearances between 1919 and 1929. The combative midfielder then joined Real Madrid and featured for them for four years, making 43 appearances and scoring eight goals.
One of the great strikers in the late 1920s, Cosme Vazquez joined Atletico Madrid from Real Vigo in 1925, but only made his first appearance for the club in 1928. In the 1928-29 season, Vazquez made 17 appearances and played every single minute for Atletico, scoring 13 goals. He joined Real Madrid in 1929 and played there until 1931, scoring four goals in 16 games.
Francesco Moraleda spent three seasons at Real Madrid between 1925 and 1928, helping the club to win three back-to-back regional championships between 1925 and 1928. After scoring 13 goals in 40 appearances for Real, the forward joined Atletico Madrid and played for them for one season.
A two-time Spanish champion with Real Madrid (in 1931-32 and 1932-33), Jaime Lazcano started his career at the club as a young midfielder. He scored 40 goals in 81 games for Los Blancos before moving to Atletico Madrid in 1935, where he spent one season.
Luis Marin featured for Atletico Madrid from 1928 to 1930, scoring 24 goals in 35 games. After a four-year gap due to unknown reasons, he returned back to Atletico in 1934, scoring five goals in 27 games until 1936 before joining Real Madrid in 1939, again after a three year gap due to unknown reasons. Marin played just 25 games for Los Blancos, scoring five goals.
Part of the great Real Madrid team that won five European Cups in five successive seasons between 1955-56 and 1959-60, Rafael Lesmes was on Atletico's books before joining Real, however, he did not make a single appearance for Los Rojiblancos. At Real Madrid, the defender made 163 appearances between 1952 and 1960.
Jose Luis Perez-Paya Soler joined Atletico Madrid in in 1950 and played three years for them, making 65 appearances and scoring 30 goals. The striker was then signed by Real Madrid where he made 36 appearances and scored 13 goals in four years.
After rising through the ranks at Atletico Madrid's academy, Paco Llorente joined their senior team in 1986. The winger played just one season at senior level with Atletico and signed Real Madrid in 1987, where he went on to make over 100 appearances. Llorente won three league titles with Los Blancos.
Joaquin Parra joined Atletico in 1987 after making 221 appearances for Real Betis. The midfielder stayed for two seasons with the Rojiblancos before signing for Real Madrid in 1989.
After gaining promotion from Real Madrid's B team, Sebastian Losada made 38 appearances for their senior team between 1984 and 1991, scoring 13 goals. Atletico signed him in 1991, but he could survive only one year at the club. Losada retired at the age of 27 and became a lawyer.
Left-back Miguel Soler joined Barcelona in 1988 and made 76 appearances for them before joining Atletico Madrid in 1991. However, after just one season with Atletico, he returned back to the Camp Nou. In 1995, he also joined Real Madrid, but the best period of his career came towards the end of his professional journey when he featured over 150 times for Mallorca between 1998 and 2003.
Juan Esnaider was one of those Real Madrid youngsters who often appeared for the first team whilst also playing for their B team between 1991 and 1993. The striker left the club to join Zaragoza in 1993 before returning back to Los Blancos in 1995 for another season. In 1995-96, Atletico Madrid came calling. In his one season with Los Rojiblancos, Esnaider scored 16 goals in 35 games.
After established spells at Cadiz and Malaga, Pedro Jaro joined Real Madrid in 1990. The goalkeeper made just four appearances for Los Blancos in his four years at the club before joining Betis in 1994 and Atletico Madrid in 1997. He just made three appearances for Atletico.
Atletico Madrid legend Jose Garcia Calvo actually started out at Real Madrid's academy before making 16 appearances for their senior team in the 1996-97 season. He joined Valladolid in 1997 and made over 100 appearances for the club until 2001. Atletico Madrid then signed him in 2001 and he played a crucial role in helping them gain promotion to the top flight in 2002.
After multiple loan deals away from Real Madrid, Rodrigo Fabri left the club without making a senior appearance as he was signed by Atletico. At Atletico, Fabri stayed just one season in 2003-04, playing 16 games.
After playing nearly 100 games for Real Madrid's academy, Jose Manuel Jurado made just three senior appearances for the club before he was offloaded to Atletico Madrid in 2006. At Atletico, the central midfielder made 88 appearances, scoring 10 goals.
After back-to-back promotions from Real Madrid's C team to B team and then to the senior team, Antonio Adan made his first senior appearance in 2010, but overall, he could just play three games for Real Madrid until 2013, reason being Iker Casillas in his prime. In 2018, he joined Atletico Madrid for two years, playing just two games.
Marcos Llorente graduated from Real Madrid's academy and went on to make 22 appearances between 2015 and 2019 for their senior team. In the summer of 2019, he was sold to Atletico Madrid, where he still plies his trade.
Sergio Reguilon graduated from Real Madrid's academy and played for their B team until 2018. He got the chance to feature for the senior team, making 14 appearances between 2018 and 2019. Reguilon then moved to Sevilla on loan for the 2019-20 season before Tottenham Hotspur signed him in September 2020. Two years later, in the summer of 2022, Spurs loaned him to Atletico Madrid until the end of the 2022-23 season.
One of the lesser known goalkeepers who played for both Atletico and Real Madrid, Jose Cabo made just nine appearances for Los Blancos before Atletico signed him in 1929. He made just 17 appearances for Atletico. He made just 54 club appearances in his career.