Other forms: handlers
In intelligence work, a handler is the officer who runs and instructs an agent. His handler, meet your handler, the handler was recalled.
The relationship is the whole of agent-running: the handler recruits, briefs, pays and protects the source, and the trust between them decides whether the intelligence is any good. Elsewhere, a handler is anybody who manages an animal or a person professionally: a dog handler, a baggage handler, a press handler. Note handle, and mishandle; and that handler in politics is faintly insulting about the people managing a candidate.
1nounhandlerThe officer who runs and instructs an agent.
“The spy met his handler secretly in a park to pass on the documents.”
2nounmanagesSomebody who manages an animal or person professionally.
“The police dog's handler gave a quiet command, and the dog lay down at once.”
handler is a manager or controller.
The word is handle plus -er, from Old English handlian, to touch with the hands. A handler is somebody who has hold of something, which describes the animal, the baggage and the agent about equally.
Middle English
handler
English, today
handler
From Middle English handler, handiller, equivalent to handle + -er.
Etymology from Wiktionary, CC BY-SA