A fictional character introduced in
DC Comics Crisis on Infinite Earths. Her primary ability was to replicate herself, existing in several places and times simultaneously. Though created for one story, the character also appeared as the "narrator" of another comic book mini-series
The History of the DC Universe. She also appeared in
Millenium,
The New Guardians and
Guy Gardner: Reborn.
As the story goes for her origin, The Monitor was watching the world from his grandiose satelite in space, making plans for his battle against The Anti-Monitor. He happened to see a young girl named Lyla down on Earth drowning, and with his abilities from on high, he pulled her out of the river and cared for her. An orphan from the flood, Lyla became like a daughter to The Monitor, and he raised her and gave her the special abilities she would need to help him defeat the enemy of the Multiverse. However, during the actual strategic battle, The Anti-Monitor tainted one of her replicants, and when that replicant was returned to her full body, it infected her mind and she was turned against the man she loved like a father. As mythic tales go, Harbinger was Judas to The Monitor as saviour. A classic plot device for tales as grandiose as Crisis.