"It was a Muggle who saw him. 'Course, she didn't really understand. The Muggles think he's just an ordinary criminal, don't they? So she phoned the telephone hot line. By the time the Ministry of Magic got there, he was gone."
Seamus Finnigan[src]

This unidentified Muggle woman is famous for having spotting Sirius Black in Dufftown in 1993. She called the police, but by the time the Ministry of Magic arrived, Black had already gone. She was mentioned in the Daily Prophet.