who'd
uk/huːd/us/huːd/short form of who had:
She wondered who'd sent her the mysterious email.
short form of who would:
Well, who'd have thought Joey was going to become so successful?
More examples
- Who'd like another piece of cake?
- I wondered who'd written the note.
- Who'd have thought that Kevin would do so well?
- He asked who'd unlocked the door.
- He is the man who'd never been on a plane.