Cyber-Leader's subordinate

During the Master's Dalek Plan, the Cyber-Leader, itself a follower of, was supported by a subordinate CyberMaster.

Characteristics
Of the CyberMaster ranks seen in the Master's Dalek Plan, the subordinate was the only other CyberMaster seen to sport a Gallifreyan cloak and headdress in place of the side handles on the Cyber-helmet other than the Leader. It was distinguished from the Leader by the black colouring of its headdress, in contrast to the Leader's silver. (TV: The Power of the Doctor)

Biography
During their attack on the Toraji Transport Network, this CyberMaster informed the Leader that the Thirteenth Doctor's TARDIS had been detected making a rescue attempt. Along with the Leader, it was present at the Winter Palace in 1916 when who appeared to be the Fugitive Doctor arrived. Not knowing that she was an AI hologram, the CyberMasters opened fire only to kill themselves in an example of the old circular firing-squad gag, with the energy that would have regenerated them being used to reverse the forced regeneration forced on the Doctor by the Master. (TV: The Power of the Doctor)

Behind the scenes
The position of this CyberMaster is equivalent to the First Cyberman from Revenge of the Cybermen and the Neomorph Cyber-Lieutenants from later stories in the classic series of Doctor Who. Curiously, a black headdress is used to distinguish it from the silver of the Leader, whilst Cyber-Leaders have been generally distinguished from subordinate Cybermen by black side handles.