Operation Galaxia (Spanish: Operación Galaxia) was the codename given to the plan which preceded the 23-F attempted coup d'état in Spain. It was named Galaxia, because the officers who took part met in Cafetería Galaxia in Madrid (later known as Van Gogh Café, and as of 2019 is a Taco Bell), on 11 November 1978.

It was meant to take place on 17 November 1978, to stop the Spanish transition to democracy taking place at that time. That date was chosen because the King, Juan Carlos, would be away in South America. The three people in charge of the operation were Guardia Civil Lieutenant-Colonel Antonio Tejero, Major Ricardo Sáenz de Ynestrillas Martínez, and another colonel, whose name has not been revealed.

An Infantry Captain of the Police, and an Infantry Commander of the Army were present at the conversation, and informed their superiors of the plot.

On 8 May 1980, the two main suspects, Tejero and Ynestrillas Martínez, were court-martialled, and on their way, they were cheered by crowds with nationalist flags, but also insulted, which showed the division of Spain at that time. The attorney general asked for six years for Tejero, and five for Ynestrillas Martínez, but they were only given seven months and a day and six months and a day respectively, the minimum sentence. Neither of them lost their military rank, and Ynestrillas Martínez was later promoted to Commander (Major).

In 1986 Ynestrillas Martínez was assassinated by Euskadi Ta Askatasuna (ETA) along with Lieutenant-Colonel of the Infantry Carlos Vesteiro Pérez, and their driver Private Francisco Casillas. As the car they were travelling in approached Ynestrillas Martínez home on Avenida del Manzanares, Madrid on 17 June 1986 two members of ETA who had been lying in wait opened fire on the car killing all 3. Ynestrillas Martínez was 50 at the time of his death.^[1]

Lieutenant-Colonel Tejero attempted another coup on 23 February 1981, in the middle of the voting by the deputies for the new Prime minister. He took over the Cabinet and lower house of Parliament with 200 men, holding 350 deputies hostage and announcing the constitution of a military junta. This became known as the 23-F coup.

• Clemyn-Jones, Bill (23 February 1981). "King Orders army to crush coup". The Guardian. Retrieved 2007-02-26.

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