TARDIS Index Files

TARDIS Index Files was a YouTube series that showcased Doctor Who aliens and villains, explaining their histories and what they're capable of.

They are presented by the TARDIS scanner in the Twelfth Doctor's control room. Like Mr Smith's data updates and the Monster Files, they were presented from an in-universe perspective with no references to the "real world" outside of the "Subscribe" end screen.

The Index Files were a monthly feature on the official Doctor Who YouTube channel, and feature illustrations from Rachael Stott.

BBC America
On 23 November 2013, the BBC America YouTube channel released a "stats" file on the Zygons for the 50th anniversary. The video was nearly identical in content to the later Who Are The Zygons, except that it took place in the Eleventh Doctor's Victorian TARDIS, and did not feature information from series 8. The BBC America version is actually much more detailed than the later Index File.