During the years that Harry Potter was living with the Dursleys, before his fateful eleventh birthday, some wizards and witches spotted Harry — and were spotted by him.
Yet sometimes he thought (or maybe hoped) that strangers in the street seemed to know him. Very strange strangers they were, too. A tiny man in a violet top hat had bowed to him once while out shopping with Aunt Petunia and Dudley. [...] A wild-looking old woman dressed all in green had waved merrily at him once on a bus. A bald man in a very long purple coat had actually shaken his hand in the street the other day and then walked away without a word. The weirdest thing about all these people was the way they seemed to vanish the second Harry tried to get a closer look.
Harry Potter and the Philosopher's Stone, chapter 2 – "The Vanishing Glass"
We know the first of those was Dedalus Diggle.
"I've seen you before!" said Harry, as Dedalus Diggle’s top hat fell off in his excitement. "You bowed to me once in a shop."
Harry Potter and the Philosopher's Stone, chapter 5 – "Diagon Alley"
Who were the other two, the "wild-looking woman dressed all in green" and the "bald man in a very long purple coat"?