Dead Red is the Unchained Memory of a pegasus railroad worker killed during the rebuilding of the railway between Ponyville and Dodge City. He survives by feeding from strong emotions, most notably fear. He helms The Treasure Express's (formerly the Appaloosa Special) spectral iteration. He is never directly named; his moniker is an epithet taken from grafitti at the Ponyville Tri-Rail Station.
Though he may have originally been one pony, his form in the novel is more an amalgam of all ponies who died reconstructing the Pan-Equestrian Railway.
He is destroyed when Sirocco shears his memory anchor (his bronze badge) in half.
Whether the return of Unchained Memories entails the actual resurrection of a spirit or is simply a spirit thinking it is a reanimated individual is left up to the reader.