Wikipedia Profile

Dr. Sam Isaacs (played by Iain Glen) is a scientist employed by Umbrella. The character of Dr. Isaacs was named after the actor Jason Isaacs, who was originally considered for the role and provided a voice over narration in Resident Evil. At the time, Isaacs' role was credited as "Dr. William Birkin/Narrator", and after he could not make an appearance in Apocalypse, Iain Glen was brought in. The character was then changed to Dr. Isaacs.

Resident Evil: Apocalypse

First introduced in Apocalypse, he was involved in the creation of the Nemesis program with Major Timothy Cain, after Dr. Birkin was removed from the project. He was head of a team of scientists at the Raccoon City Hospital who experimented on Alice. After the Raccoon City incident, he continued further experimentation at a Umbrella laboratory in Detroit. He gave her a variety of telekinetic abilites. After Alice's escape, Isaacs activated "Program Alice", putting her under Umbrella's control.

Resident Evil: Extinction

In Resident Evil Extinction, Dr. Isaacs has replaced Timothy Cain as North American Operations Director and is Head of Umbrella Sciences Division. He has been tasked with finding a cure to the zombie plague that has swept the globe. Using blood samples from Alice, Dr. Isaacs and his team of scientists were able to create clones of Alice. Umbrella Chairman, Albert Wesker, has 100 clones created. Through tests of survival, many of the clones have failed to live up to the expectations of the original Alice. Dr. Isaacs defies orders against his second in command, Slater, and Albert Wesker. During one of the holographic meetings with the Umbrella executives, Dr. Isaac records Wesker's voice, to give the order allowing Dr. Isaacs the resources to go after Alice and capture her. Using his newly created Super-Undead against Alice and her friends, Isaacs is bitten by one of them and retreats back to the Umbrella base - an underground outpost similar to The Hive. To prevent further infection of the T-virus, he attempts to use the anti-virus to cure himself and injects himself with multiple vials of the sereum. He is then shot by Slater following orders from Albert Wesker, however, Isaacs survives and kills his second in command with his mutated hand, stabbing him through the eyes and mouth. Isaacs proceeds to kill everyone at the base. Isaacs, due to the increased infection from the bite and the anti-virus, mutates into a Tyrant- like creature. He is killed by Alice, after being lead into a replica of the security corridor leading to the Red Queen's Chamber from the original Hive facility as part of Project: Alice's training. The laser grid activates and kills him, as it did to One in the first film.