Isaac Kleiner

Doctor Isaac Kleiner is a fictional character from Half-Life and Half-Life 2. An archetypal 'absent-minded genius scientist', he is a prolific author of several works on teleportation and interdimensional travel, and one of the few survivors of the incident that took place in the Black Mesa Research Facility. Later on, he becomes a key (if somewhat self-conscious) leader of the Resistance against the Combine Empire, and a prime member of the Resistance's science team.

He is affectionately referred to simply as "Izzy" by Dr. Eli Vance on various occasions. Some sources also erroneously refer to the character as Dr. Alex Kleiner, based on an apparent inaccuracy in the strategy guide of the original Half-Life.

Half-Life
Although Dr. Kleiner's character design is based on the "bald, glasses" scientist model from the original Half-Life (dubbed "Walter Bennett" by fans and later named as such in the Opposing Force and Blue Shift expansion packs) he is not intended to be the same character, and never interacted with Gordon at all during the Black Mesa Incident. Also, the texture file for Dr. Kleiner's face is called "walter_face.vtf". This is likely to be referring to Walter Bennett. Before Half-Life 2, the only reference in the games to Kleiner was during Half-Life: Decay when Dr. Keller mentions he "does not understand what Kleiner sees in that boy," referring to Gordon.

Dr. Kleiner, who recommended Gordon Freeman for employment at Black Mesa, worked with him as part of the facility's Anomalous Materials team and was one of his professors at MIT. He manages to survive the Resonance Cascade disaster of the first game with the aid of Eli Vance, though exactly how he escapes is unknown. One logical explanation is that he, Eli Vance (With his daughter Alyx) and perhaps some other Black Mesa personnel took an SUV and escaped the same way Barney Calhoun, Doctor Rosenberg, Simmons, and Walter Bennett did at the end of Blue Shift.

In the strategy guide for the original Half-Life, a Dr. Alex Kleiner is mentioned, which can be assumed to be the same person. This is likely an error, although it is entirely possible during the development of Half-Life 2 he had his name changed, and is most likely the same person mentioned at the beginning.

Half-Life 2
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 in an old abandoned Northern Petrol building. 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. As a pet, Dr. Kleiner keeps a debeaked headcrab he calls 'Lamarr' and at some points in the game calls 'Hedy' (a reference to 1930s actress and inventor Hedy Lamarr). When Barney informs him that Gordon Freeman has arrived, Kleiner tells Barney to send Gordon on his way - although he forgot that Gordon would not know the way to the lab. Alyx eventually had to rescue Gordon when he found his way, by luck, into a section of the building Kleiner hid in, but was cornered by several metrocops and was unarmed.

Kleiner introduced Gordon to his HEV Suit, then would have sent him on his way to Eli and Judith Mossman, but Lamarr interfered with the teleportation process, and only after being partially teleported to other places (including right behind Kleiner, frightening him), Gordon was teleported to the outside of the structure. He left Kleiner's lab, not to return until the Resistance rose against the Combine.

During the rebellion, Kleiner found Dog and stored him in the room that used to hold the HEV Suit. Kleiner was alone during most of the rebellion (save for Lamarr) and protected himself with a shotgun. When Gordon and Alyx teleported in from Nova Prospekt a week into the rebellion, Kleiner was very optimistic about the Resistance's odds and tried to convince Alyx of this, at which he failed. He is not seen for the rest of the game, but it can be assumed he escaped City 17.

A depiction of Kleiner's younger self is also featured in Half-Life 2, appearing on the cover of Popular Scientist, a fictional magazine (and spoof of 'Popular Science'' magazine) that would have to be published prior to the Black Mesa Incident. In it, he sported sideburns and had more hair, which is seen as brown in color. 

Half-Life 2: Episode One


In Half-Life 2: Episode One Kleiner returns, appearing on the video screens previously reserved for Dr. Breen's propaganda and instructing survivors to make their way to their nearest train station to evacuate City 17. Kleiner also amusingly informs people that the Combine's "Reproduction Suppressors" are no longer effective, and that "those so inclined" should take advantage of the fact and "do your part for the revival of the species". Alyx is quite surprised by this and asks if Kleiner really means for them to "get busy". He also rallies people to prepare for the Combine's retaliation, stating that several new technologies were developed during their occupation, and that these will be deployed as soon as possible to help fight the Combine.

Half-Life 2: Episode Two
Kleiner appears once again in Half-Life 2: Episode Two. First, he is seen beside Dr. Eli Vance and Dr. Arne Magnusson on the video communications to Alyx and Gordon, and again later on upon reaching the White Forest Base. He spends most of the game working with Dr. Magnusson on the rocket.