Decio Azzolino (11 April 1623 – 8 June 1689) was an Italian Catholic Cardinal, code-breaker, investigator and leader of the Squadrone Volante.
When the Kingdom of Naples was made aware of invasion plans by Henry II, Duke of Guise, it was Azzolino who (in February 1654) concluded that the breach must have come from Camillo Astalli, the Pope's Cardinal-Nephew.
Later in 1654, because of this service he rendered to the pope, Azzolino was elevated to cardinal and was made cardinal-priest of the church of Sant'Adriano al Foro (Curia Julia) in Rome.
Azzolino was the leader of the independent liberal movement Squadrone Volante, which played a role in engineering the result of the conclave in favour of an anti-nepotism candidate.
[4] Azzolino's Squadrone also is thought to have engineered the election of Giulio Rospigliosi as Pope Clement IX at the papal conclave of 1667.
[4] Rospigliosi, who had been cardinal secretary of state, rewarded Azzolino by immediately (on the night of his election, in fact) appointing him to the position,[3] giving further credence to the rumour.
Bargrave, again, suggested that Azzolino was sent to Romania [citation needed] by Pope Alexander in order to avoid public perception that a relationship was ongoing.