Thaleks were a powerful race that existed in an alternate timeline in which the Doctor never left Gallifrey. They conquered half of Mutter's Spiral with the weapons they devised. It was shown that they were occupied by Thal mutants rather Kaleds. Unlike Daleks, they had morals and emotions. Their casing was seen to be made of the metal that would have been used by the Thals to make the Neutronic missile in the regular universe. They also were capable of teleportation due to transmat systems wired in their casings. Some of them were even capable of falling in love, as one Thalek was devoted to a woman who resembled a Thal. (BFDWU: Auld Mortality)
- Their name suggests relation to both Daleks and the Thals. It appears that in this timeline, it was the Thals, rather than the Kaleds, that became a powerful cyborg race, the equivalent of the Daleks.
"Thaleks" was also a term coined by Charlotte Pollard to describe the Daleks that believed themselves to be Thals. (BFA: Brotherhood of the Daleks)