Dr. Isaac Kleiner is a Caucasian American scientist. An archetypal 'absent-minded genius scientist' (although somewhat more benign), 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) leaders of the Earth Freedom Fighters against the Axis, and a prime member of the Resistance science team, and became the primary leader of the resistance when Eli Vance, along with Gordon Freeman, went on a search to find and free Alyx Vance who made a deal with the G-Man to resurrect her father at the cost of her freedom, and later on the first President of the Human-Vortigaunt Federation post-Golmar Civil War. His most notable work would be the works he and Drs Eli Vance and Gordon Freeman made that became instrumental to the creation of the Kleiner-Freeman-Vance Drive Systems, the primary non-Combine, and non-Ancient method the wider Multiverse uses for multiversal travel.
