Chad Kaplan was a member of the UBCS commando team sent into the Hive to shut down the Red Queen. Kaplan was the group's computer expert, a former FBI agent who'd been recruited into Umbrella by One (an offer he instantly accepted since he'd get to do field work as a member of the U.B.C.S.). Kaplan was directly responsible for turning the Red Queen off, and later it was he who fried and completely destroyed the malignant supercomputer. He was eventually killed by the Licker aboard the train.
His name is given as Bart Kaplan in the film novelization by Keith DeCandido.