Dr. Isaac Kleiner

Dr. Isaac Kleiner is a fictional character from the computer games Half-Life and Half-Life 2. He is one of the few survivors of the incident that took place in the Black Mesa Research Facility.

Dr. Kleiner worked with Freeman as part of the Facility's Anomalous Materials team. He manages to survive the Resonance Cascade disaster of the first game; how he escapes from the Facility is not known. Along with colleagues (and fellow survivors) Alyx Vance, Dr. Eli Vance, and Barney Calhoun, he makes up the core of the resistance against the Combine. Dr. Kleiner has set up a lab underground in City 17. A teleportation system, developed jointly by Kleiner and Vance, allows for near-instantaneous transportation between Kleiner's lab and Vance's facility, several miles distant.

Dr. Kleiner lives with a pet headcrab, which he has named Hedy Lamarr, after the actress.