T0-D interrogation droids were a variety of torture droid created by the Empire. Equipped with various stunning and damaging weaponry, they were used by the Imperial Security Bureau to illicit information from captives. They were numerous aboard the Death Star.
IT-O Interrogator droids were small spherical hovering droids designed by the Empire to question prisoners. IT-Os were originally exclusively used by the Imperial Security Bureau, IT-Os found their way into broader Imperial use as the rumors of their effectiveness spread. They were equipped with truth chemicals and many instruments capable of causing extreme pain.
Source:The New Essential Guide to Droids (Art: Ian Fullwood; 2006)
First Appearance: Star Wars: From the Adventures of Luke Skywalker (1976)