Apparently reptilian, the Bandrils lived on a planet near Karfel. The Bandrils' relationship with the Karfelons was sometimes friendly. The Bandrils subsisted in part on grain from Karfel. (TV: Timelash)
Sometime before 1969, the Bandrils were conquered by the Dominators, although that may be part of the usual propaganda the Dominators spread. (PROSE: Mutually Assured Domination) Late October 1969, Colonel Douglas of the Fifth Operational Corps lead a platoon to deal with Bandrils in the highlands of Argyll. (PROSE: The Lost Skin)
The Bandrils tried to invade Earth before 1997. UNIT fought them off without the Doctor's assistance. (PROSE: The Dying Days)
The Eighth Doctor and Charley Pollard once visited a Bandril spaceship. (AUDIO: Time Works)
Bernice Summerfield learned of a potential dig site on Javarda from a Bandril trader on Jovellia. (WC: Dead and Buried, AUDIO: Resurrecting the Past)
Bandrils attended Garundel's auction for weaponry. (AUDIO: Starlight Robbery)
A Bandril named Calarch attended the Enormous Storage Co. auction in COMIC: Space Invaders!
Other references
The Bandrils were on the Eleventh Doctor's top five enemies list which he mentioned to the Fourth Doctor and Romana II while they were making up "top five" lists. (AUDIO: Babblesphere)
Behind the scenes
Lance Parkin has stated that the Bandril invasion reference was a joke, based on the Bandrils being "rubbish" monsters, and that "some alien invasions were beneath the Doctor's dignity to deal with". [1]