A fair few in my time....
But the one which stands out is the 'Dew Drop Inn' in New Cross. One of the more lively pubs in the area with a decent line in bands.

We were regulars there and one day noticed that a square of carpet at our favourite leaning spot by the bar had been removed, so asked the barmaid when it was coming back. It transpired that the previous Saturday the guy we'd been chatting to, after we'd left to get some dinner, had stabbed (to death) the next occupant of said carpet. When the police released the tile, it never did look quite the same.

[Also the Yates Wine bar next to Newcastle Rail Station that my mate claimed was 'upmarket' - pair of squaddies fighting with pool cues even before we'd got to order the beers. Or, the seaside pub in Skegness that my then girlfriend picked in time to get a ringside seat on a massive fight - the barstaff obviously had it sussed as they waited until the protagonists reached the bar before pulling out the shinty sticks and sorting out the miscreants]
(baldybeardy, Fri 7 Feb 2014, 22:37, Reply)