A leader was someone who in charge of others.
Cyber-Leader was a rank used by the Cybermen, (TV: Revenge of the Cybermen) above Cyber-Lieutenant and subordinate to the Cyber-Controller. (TV: Earthshock, Attack of the Cybermen) It included the divisions of Senior Leader and Junior Leader. (PROSE: Attack of the Cybermen) Cyber-Leaders were typically denoted by their black side handles of the Cyber-helmet, (TV: Earthshock) while others had additional black headblocks (TV: Revenge of the Cybermen) or black faceplates, (TV: A Good Man Goes to War) while only the corners of Leader Ashad's side handles were black. (TV: Ascension of the Cybermen) Early CyberMondasian leaders had no such distinguishing features. (PROSE: Doctor Who and the Tenth Planet)