Spanish Inquisition
Unlike their Imperial counterparts, the Spanish Inquisition does not shove Inquisitorial retinues up your ass whenever you commit the slightest of offences. It was however probably inspired by it, or at least, the romanticized version of it, with the grim dark turned up more than a few notches of course.
The real-life Spanish Inquisition were a combined political/religious party formed in 1480 by the Spanish Monarchs Ferdinand II of Aragon and Isabella I of Castile. It was intended to maintain Catholic orthodoxy in their kingdoms and to replace the Medieval Inquisition, which was under Papal control. While the groundwork was laid in AD 1478, the Spanish Inquisition was in power from 1480 to 1834 - 356 years (using 1478).
The Spanish Inquisition is often stated in popular media and medieval history as an example of Catholic intolerance and repression. Modern historians now question or disagree with earlier accounts concerning the severity of the Inquisition. Henry Kamen asserts that "the 'myth' of the all-powerful, torture-mad inquisition is largely an invention of nineteenth century Protestant authors with an agenda to discredit the Papacy".
Modern estimates based on incomplete records put the total number of trials from 1540 to 1700 at around 87,000 with executions in persona at around 1300. Those who manage to escape the Inquisition before they were executed were instead executed in effigy; that is, an effigy of the accused was burned in their place. "Executions" in this manner (again, from 1540 to 1700) numbered at around 770. This is a death rate of less than 1-in-50, not factoring in just what crimes (actual or contrived) the people were executed for, and contradicts the blood-soaked reputation the Spanish Inquisition is often given.
They are often associated with (or reviled for) using torture in popular perception and media, even while it was standard operating procedure for courts secular or not at the time. Methods of torture included:
Strappado: binding the victims hands behind their back and suspending them by their wrists. Sometimes a series of drops would be added, jerking the victim up and down and forcing their arms out of their sockets. Weights could be added to the victims body to make the hanging even more excruciating.
Toca, or waterboarding: securing the victim to an inclined board and binding them so that they cannot move. Then the victim is gagged and has a cloth placed over his or her face, and water poured over it. Toca gives the victim a feeling of drowning, even if no water enters the nose or mouth. CIA agents go through it as part of their training and on average last only 14 seconds before begging to be released.
The Rack: often considered the most painful of tortures by contemporaries. The victim had their hands and feet bound to rollers at opposite ends of a frame. In theory, the torturer would turn the rollers and the chains attached would dislocate the joints of the victim. If the torturer continued to turn the rollers the victim's arms and legs would be torn off. (Probably not true, tendons and ligaments are incredibly strong. Reports of people being pulled apart by horses mention that they have to be helped by cutting the joints a bit to get the process started. Who knows though, maybe ratchets are just that effective, and some people spent a long time on the rack, which might loosen them up some.)
There were, however, regulations for the Spanish Inquisition on how far the torture could go; no removing body parts and nothing that resulted in death. The first head of the Spanish Inquisition (the infamous Torquemada) made frequent use of torture, a less known fact is that that the Pope at the time went to the King and Queen of Spain to try and rein in his cruelty. Despite this the Spanish Inquisition are known to have been fairer, and used torture less often, than the secular courts at the time. There were several cases where people were on trial in secular courts for lesser crimes who would blaspheme in the court room just so they could be tried by the Spanish Inquisition instead, who would give them a fair(er) trial.
In an early shout-out to 40k, in 1256, Pope Alexander IV decreed that inquisitors could clear each other from any wrongdoing that they might have performed during torture sessions, except this decree was for the Medieval Inquisition and predated the Spanish Inquisition by over 150 years.
Victoria Lamb makes some pretty badass Spanish Inquisitorial models.
The Spanish Inquisition is not to be expected. ( Despite the fact that they were legally obliged to give thirty days notice. )