Overview
The Prior of Crato (Prior do Crato), was the traditional title given to the head of the Order of the Knights of St. John of Jerusalem (Hospitaller) in Portugal. It is a reference to the domains of the order around Crato, Portugal.
The Portuguese branch of the Knights Hospitaller was originally based in the northern citadel of Leça do Balio (near Matosinhos), which was allegedly donated to the order as early as 1112 by Countess Theresa. Around 1232, King Sancho II of Portugal donated extensive domains further south, around Crato (in the Portalegre District) to the Knights Hospitaller, along with the duty to fortify that frontier. The order moved its headquarters from Leça to Crato in 1340, shortly after the Battle of Salado, constructing the Monastery of Flor da Rosa near Crato.
From the outset in the 12th century, the head of the Order of Knights Hospitaller in Portugal was known simply as the Prior do Hospital. That title continued to be used after the move to Crato. It is really only after 1441 that the term Prior do Crato began being commonly used.
The most famous person to hold this position was probably António, Prior of Crato, a royal prince who attempted to lay claim on the royal throne (as King Anthony I of Portugal) during the 1580 dynastic crisis. Anthony ended up losing his bid to King Philip II of Spain.
From Wikipedia (CC BY-SA 4.0).