Alex

Alex is a technician working for Abstergo Industries and the assistant of Dr. Sophia Rikkin in the Abstergo Foundation Rehabilitation Center in Madrid.

In charge of the Animus, Alex assisted Rikkin while the various descendants of Assassins captured by the Templars were put into the device to explore the memories of their ancestors. In 2016, Alex was once again behind the Animus console while his bosses were overseeing the session of Callum Lynch, a man they hoped would lead them to an Apple of Eden lost during the Spanish Inquisition.

Later, after Lynch eventually discovered the location of the Apple while exploring the memories of his ancestor Aguilar de Nerha, Alex witnessed Lynch somehow took control of the Animus to communicate with his Assassin ancestors.

Reference

 * Assassin's Creed