A weasel was a type of animal from Earth.
While having dinner at Nest Cottage with Mike Yates, the Fourth Doctor was attacked by a stuffed weasel. (AUDIO: The Stuff of Nightmares)
An anthropomorphic weasel was a coachman from Pantoland. (PROSE: Oh No It Isn't!) The Masked Weasel was an anthropomorphic weasel from the Crooked World. (PROSE: The Crooked World)
The Companions of the Panjistri had weasel-like features. (PROSE: Timewyrm: Apocalypse)
Fey Truscott-Sade first encountered the Eighth Doctor in an adventure involving psychic weasels in Russell Square. (COMIC: Tooth and Claw) Izzy Sinclair was also present during this adventure. (AUDIO: Izzy's Story)
As he admitted openly on the conspiracy website Who is Doctor Who?, Marky had a "morbid fascination" for weasels, which he suggested that aliens might understand. (PROSE: Henry Van Statten [+]Unknown, Who is Doctor Who? fiction (BBC, 2005).)
Weasel was sometimes used as an insult. Charley Pollard called the Kro'ka "a little blobby weasel." (AUDIO: The Next Life) Tegan Jovanka called Vislor Turlough a weasel when he revealed to the Witch Guard that only the Fifth Doctor and Nyssa knew how to fly the TARDIS. (AUDIO: Heroes of Sontar) Ace called a security guard at Windsor Castle "weasel features." (TV: Silver Nemesis)