Necro-Overs are humans in Kamen Rider W Forever: A to Z/The Gaia Memories of Fate, who were brought back from the dead and turned into super soldiers whose physical capabilities in all areas surpass humans and even some Dopants, as well being unkillable by conventional means. However, they require regular injections of bio-stimulants to keep their bodies from breaking down. The research on these super soldiers was formed by a collaboration of both the Museum and Foundation X lead by Mikki Daido (who took the name Maria S. Cranberry when she took the fake identity of an Interpol agent to fool Philip) based on Raito Sonozaki's death and revival after falling into the Gaia Memory.
Necro-Overs are technically dead, evident as their bodies feel cold instead of warm, and usually crippling physical damages, like broken bones, don't impair their movements much. Personality changes also occur over time, most notably the loss of empathy and the lack of fear of death, as well as gradual loss of memories when they were alive. Like any humans though, they are also highly compatable with certain Gaia Memories. Unfortunately, they turn to dust when hit with a Kamen Rider's Maximum Drive, or a Scanning Charge as seen with Kamen Rider OOO, they also become destabilized if injected with a bio-stabilizer blocker solution, which is only reversible if treated with an antidote quickly. One particular Necro-Over, Katsumi Daido is a refined Necro-Over, as well as the first. He lead the Necro-Overs and founded NEVER, a shortened version for NECRO-OVER. He plotted to make the entire population of Futo City into Necro-Overs through the T2 Gaia Memories. Fortunately, this plan was stopped by Kamen Rider Double and Daido was defeated and all T2 Gaia Memories were destroyed.