Lifesaver (ライフセーバー Raifusēbā?) works as the Maverick Hunters' medical control officer in Mega Man X5. He runs virus tests and builds vaccines to protect against them, and is very knowledgeable of the Sigma Virus and its properties. He's also responsible for general medical duties, such as when he picked up the exhausted Zero after the Shuttle mission. Lifesaver was always suspicious of Zero's virus readings, as the virus seemed to have no effect on him. When the Zero Virus broke loose, his suspicion grew even greater. When X confronted Zero about his condition, he immediately accuses him of being infected.
Some scenes seem to indicate that there is more than one Lifesaver, suggesting that all Lifesavers are from the same mass-produced model. While this may be the case, in the events following the crash of the Eurasia, they/he made no further appearances with the Hunters during the Nightmare Outbreak, nor during the war between the Maverick Hunters and Red Alert or the incident with the Jakob Project.