Commander (XCOM 2)
The Commander is the player character in the XCOM series. The player is never named in dialogue, and always referred to simply as "Commander".
The Commander was captured by the aliens when XCOM fell a couple of months in to the alien invasion, and was held captive in an alien laboratory. Upon researching the alien implant implanted in their brain, it seems the Commander was connected to the alien psionic network, constantly running tactical simulations for the aliens, likely unwittingly serving as their battle computer.
Twenty years later, Bradford had established the resistance to the point where rescuing the Commander was possible, and personally led the mission to pull them out of the alien stasis chamber. After removing the alien implant from their brain, the Commander was given complete command of the Avenger and the resistance as a whole.
After successfully leading the resistance campaign against the aliens, the Commander personally leads the mission to assault the Alien Fortress, due to being the most suitable candidate to link with the Avatar. When linking with the Avatar a vision of an Ethereal is briefly seen as the Commander goes under.
After killing the enemy Avatars, the Commander shows an extremely high aptitude with the Avatar's psionic power, personally holding open the exit Psi-Gate for long enough for the soldiers to evacuate, then defeating the remaining Ethereals in a psionic duel as the fortress collapses.
The events in the Bureau prequel show that Ethereals are able to bind to humans, giving them extraordinary abilities. The vision of the Ethereal the Commander has while bonding with the Avatar quite strongly suggest that the Commander may be bonded with an Ethereal, explaining their incredible tactical and strategic skill. In addition, the Commander shows an extremely high level of psionic ability while possessing the Avatar, especially in the final moments of XCOM 2, holding open a Psi-Gate and defeating several Ethereals in a psionic duel.