Silas Archer

"Silas Archer recently accepted a post as the Headmaster of the Tarsus Academy for Girls in New Cairo. Not a lot is known about Mr. Archer, except that he comes highly recommended from a private school in England. It has been his misfortune to preside over a crisis at Tarsus involving the disappearance of two of his students. To date, he has confronted parents’ fears head-on with assurances that he is doing all he can to resolve the crisis, but many who meet him come away whispering that he may not be wholeheartedly committed to the task of safeguarding the children in his care."

- Deus Ex: Invisible War description

Silas Archer is the Headmaster at the Tarsus Academy for Girls in New Cairo in 2072, whose students are mysteriously disappearing.

Background
When questioned about the disappearances, Archer dismisses them as a mere prank. He also states that he's been at the Academy too long, and that "This job is almost finished."

Upon looking for the missing children Abana Khodair, Eeva Nassif and Jennifer McAllister, Alex finds a secret office in the Academy, revealing files that Archer is actually a Lieutenant in the Knights Templar. He plans to terminate the most promising students before they can be "corrupted" by biomodification.

The player can either confront Archer with evidence of his Templar affiliation, which will trigger a firefight against him and the Tarsus Academy's SSC guards, or report him to the Standard Security Corporation guards in their HQ in the Arcology, prompting his arrest of which the player hears in a news bulletin after he leaves Cairo.

If he survives (either by being arrested, or the player simply not doing anything against him), Silas reappears during the player's second visit to Cairo as one of the two Templar assassins sent to stake out Leila Nassif's family apartment. Silas appears at this point even if he was arrested previously; presumably the Templars freed him when they took over the Arcology.