While there appear to have been several Cyber-Leaders, it is unclear if their existence overlapped. Leaders were of sufficient value to warrant a personal guard of Cybermen. (DW: Earthshock)
A Cyber-Leader was in command of an ancient Cybership which attempted to destroy the planet of gold, Voga, to stop the production of glitterguns. It was killed when its ship was destroyed by the Vogan rocket Skystriker. (DW: Revenge of the Cybermen)
A Cyber-Leader planned to destroy Earth with Cyber-bombs to stop a conference leading to an alliance against the Cybermen. When its androids were destroyed and the bomb had failed, it sent the Cybermen to attack Briggs' freighter. Its cargo, unknown to the crew, was an army of Cybermen. They awoke and took over the ship. The Cyber-Leader planned to destroy life on Earth by hitting it with the craft they had reprogrammed. The craft was taken back in time by the Fifth Doctor. It hit the Earth and wiped out the dinosaurs. The Cyber-Leader attacked the Doctor, Nyssa and Tegan Jovanka in The Doctor's TARDIS. The Doctor ground Adric's gold star badge into the Cyber-Leader's chest. It shot at the TARDIS console and died when the Doctor shot it several times. (DW: Earthshock)
The Doctor uses Adric's badge to damage the Cyberleader because it was made out of gold. (DW: Earthshock)
A Cyber-Leader commanded a squad Time Scooped by Borusa to the Death Zone. It found the Doctor and the Master and fired at them. The Doctor escaped with the Master's homing beacon while the Master tricked the Cybermen into working with him to destroy the Time Lords. They went to a giant chessboard in the Dark Tower. When the Cybermen attempted to cross, they were all electrocuted. The Cyber-Leader asked why the Master had betrayed them. He told him the safe path changed with every journey. When the Master showed the Cyber-Leader the safe path under threat of death, he turned around and killed the Cyber-Leader. (DW: The Five Doctors)
A Cyber-Leader was second in command to the Cyber-Controller in its attempt to time travel and destroy Earth in the year 1985 so Mondas would not be destroyed the next year. He and the Cyber-Controller were shot dead by the Sixth Doctor. (DW: Attack of the Cybermen)
A Cyber-Leader led a shuttle to Earth in 1988 to find the Nemesis and, upon arrival, they massacred the Neo-Nazis whom they encountered at their landing site. The Cyber-Leader was wounded by a gold coin shot by Ace, but he survived and shot De Flores dead when he held the bow. The Cyber-Leader was killed by Richard Maynarde, who stabbed him with Lady Peinforte's gold arrow. (DW: Silver Nemesis)
A Cyber-Leader commanded the Twelfth Cyber Legion in the 52nd century. It, like its predecessors, had black handle bars on his helmet, but also had a black face and a transparent "window" through which its brain could be seen, similiar to the Cyber-Lord of Pete's World. (DW: The Next Doctor)Rory Williams went to the Cyber-Leader's Cyber Ship and confronted it to learn the location of Demon's Run. Part of the fleet was then destroyed by the Eleventh Doctor, just to make a point to the Church's Anglican Marines and the Cybermen. (DW: A Good Man Goes to War)
