The British actor fell victim to a thief who stole his credit card, but he was more annoyed when he discovered the crook had used it to create fake profiles for Grint on lonely hearts websites.
The stunned screen star tells Britain's Daily Star newspaper, "I don't usually care about money that much. But when I had my card taken, I cared about that.
"And the guy who did it joined loads of different dating sites. I kept getting post and messages about it all the time. People must have thought it was me joining."