The UNIT Family was a multi-part documentary looking at the UNIT era of Doctor Who. It consisted of interviews with cast and crew from the period. Part one was released on the DVD of Inferno, and part two was released on the DVD of Day of the Daleks. The third part was included on the DVD of Terror of the Zygons.
For the purposes of this list, a "DVD documentary" is one made especially for the Classic Series DVD range. For this reason, things like studio recordings, film trims/inserts and other documentaries featured on DVD releases are not included below.