The Talosians. Their telepathy and projection of illusions could extend far beyond their home planet as shown in TOS: The Menagerie.
Probably the Q. Or barring that the Borg.
The Q aren't telepaths. They're just omniscient. The Borg must have some telepathic ability, because Picard can "hear their song" even after being de-assimilated. ProfessorTrek 01:45, July 1, 2011 (UTC)
^^The Borg are not telepaths, they communicate through their technology. Picard stated in ST:FC that not all of the Borg technology was removed.
What about the Melkot they had Talosians like abilities?
What about species 8472? They were telepthic.Gormagon 21:03, August 7, 2011 (UTC)
Seriously how can you believe the Q don't have telepathic abilities. They can move through time, create whatever objects they want, bring people back from death, and have an unlimited number of other powers. For the Q reading a person's mind would be a simple matter.