Board Thread:The Panopticon/@comment-121.45.54.78-20130925110520/@comment-1506468-20130925111643

The Master was shown in flashbacks in Death of the Doctor and Mawdryn Undead. He has a tiny cameo whilst the Doctor is regenerating in The Caves of Androzani, and his voice can be heard in some of the scenes of Journey to the Centre of the TARDIS.

Hope that clears things up! :)