We have Dirty Harry (aka. Fat Harry). Not quite on the level of some of the others posted, but can usually be found sat in the bus stop perving on kids and schoolgirls, asking for money and making the place smell like shit. He doesn't wash so you can smell him from a good few metres away, and is banned from some shops for this very reason. Here's a video of him sat watching kids:
http://www.youtube.com/watch?v=P06zLn6rWbM&feature=related
When I worked in a shop in the town centre we used to get loads of crazies coming in. Alas, I don't know any of their "official" names, so couldn't find any vids or pics.
The two who stand out in my mind are: Caterpillar Man, who came into the shop wearing only a green sleeping bag, stood facing a wall and walked sideways round the entire perimeter of the shop like a crab, and then walked out of the shop and down the street normally as if nothing had happened and he wasn't a guy wearing only a sleeping bag.
Then there was 'Scary Mary', who saw me watching her walk down the street through the shop window. She was walking along normally until she spotted me looking at her, then suddenly ran in the shop all hyped up like there was an emergency and shouted "Are you safe in here?!... Are you?!" I told her I was. She continued... "It's not safe when people can just look at you through windows you know!" She didn't like the amused look I gave her, so she came right up to my face and shouted "OH GREAT! I BET YOU THINK I'M A FUCKING WEIRDO NOW DON'T YOU?!" Then she went quiet again, shook her head and left. Pretty scary stuff when you don't expect it and she's brandishing a mean looking walking stick in your face.
There were many others but most of them just a sad look into the future of where we are all bound to end up: Old, don't know what day it is, walking round town in a dressing gown and slippers and smelling strongly of piss (a la 'Cat Piss Lady').
Oh and whilst looking for videos of these lot, I found
this. Not from Wigan, but hilarious. Anyone from Croydon know these golden oldies?