Maston

Mastons are large predators native to Sentimenous Virgo. They generally weigh around 120 kg and are around 2.10 metres tall. Mastons are large and hairy and have a powerful tail. They can easily overpower a Human, but they aren't especially intelligent.

A sexually aroused Maston secretes an airborne toxin which paralyses any animal lifeforms in its immediate vicinity. The exact range of this effect is unknown. This is speculated to be an evolutionary adaptation designed to ensure that an exhausted post-coitus Maston will not have to look too far in order to find its next meal. (''Slipback (novelisation) )

The Mastons were driven to extinction millions of years ago when their planet was destroyed. The computer of the Vipod Mor brought a Maston forwards in time to attract a Time Lord and to distract the crew. (BBCR: Slipback)