An Aldebaran serpent is an animal with three heads, possibly from Aldebaran. Q appeared as an Aldebaran serpent in 2365. In 2374, Jean-Luc Picard asked Q if the Aldebaran serpent was Q's true form, but Q told him it was just another guise like his Human form. (TNG episode: "Hide and Q", TNG - The Q Continuum novel: Q-Space) In 2380, Q again transformed into an Aldebaran serpent when banned from the Q Continuum to see if he'd also lost his powers. (TNG novel: Q & A) Malic had a PADD that was adorned with an image of fighting Aldebaran serpents. (DS9 - Gateways novel: Demons of Air and Darkness)