Bennett

Doctor Bennett was a civilian doctor working in an alternate reality of the SGC. He is briefly seen working on a project with the alternate Major Samantha Carter on an experiment to extract small amounts of energy from thousands of alternate realities, before the two are killed during the experiment.

Summary
Doctor Bennett assisted Major Carter on a project in which energy would be extracted in small amounts, from thousands of alternate realities in order to avoid the harmful effects that exotic particles could have on either of the universes connected by the bridge. At the precise microsecond that Major Carter was tapping into Lieutenant Colonel Carter's universe, Colonel Carter was out of phase, and she was transported across an inter-universal bridge along with the entire contents of the room enclosed in her lab's force shield were transported across the bridge and into Major Carter's reality. At that moment that Carter was being drawn in, Maj. Carter's equipment overloaded and exploded, killing her and Dr. Bennett and leaving no trace of them behind. Carter shifted herself back from being out of phase, only to find that she and her equipment had replaced what was there before.

It is possible that a Doctor Bennett also exists in the reality Colonel Carter is from, however, there is no indication or reference that he is in the SGC or if he ever existed at all in her reality.