mysterious thief; phantom thief
A stylish, elusive thief in fiction, often with a code of honor; not a common criminal.
The phantom thief stole a famous painting from the museum.
A phantom thief appeared at the museum in the middle of the night.
He escaped with a technique as brilliant as a phantom thief.
The culprit called himself a phantom thief and sent a warning letter.
The detectives have been chasing the phantom thief for years.
盗賊 is an older, more general word for bandits or robbers, while 怪盗 specifically evokes a clever, glamorous phantom thief of fiction.
強盗 is a violent robber who uses force or threats, while 怪盗 is a non-violent, mysterious thief admired for cunning rather than feared for violence.
Compound of 怪 (mysterious) and 盗 (thief). The exact historical origin is uncertain, but the term is strongly associated with fictional gentleman thieves.