35mm

 is a standard film format, so named because of its 35-millimeter width. It is the largest format ever used for the recording of anything to do with Doctor Who. Because of its relatively high cost, it was infrequently used for principle recording, though it was sometimes used by BBC Enterprises for telerecording.

By far, the most ambitious use of 35mm was in the recording of the 1996 telemovie, which is the only Doctor Who story, as of 2011, to be entirely filmed in the format.