What is the name of the planet where the Time Lords originate?

The planet where the Time Lords originate is Gallifrey.

Gallifrey is the fictional home world of the Time Lords in Doctor Who. It is located in the constellation of Kasterborous and is commonly depicted as a yellow-orange planet beneath a burnt-orange sky. The Time Lords’ capital, the Citadel, contains their governing institutions, archives and the Academy where young Gallifreyans train.

The planet is central to the Doctor’s identity. The Doctor is a Time Lord who fled Gallifrey in a stolen TARDIS and travelled through space and time, generally rejecting the non-interference policies of traditional Time Lord society. Gallifrey is also associated with Rassilon, one of the founding figures of Time Lord civilisation.

Gallifrey is sometimes confused with Skaro, the Daleks’ home world, or Mondas, the Cybermen’s original planet. Trenzalore is another important Doctor Who location, but it is connected to the Eleventh Doctor’s later history rather than the origin of the Time Lords. In the revived series, Gallifrey’s fate is closely tied to the Last Great Time War.