Three nasty-ish ones.
First one totalled my lovely old 'sun super' bike back in '96. Cycling home in the evening, wearing high-viz with lights on, car behind me flashes his headlights and the van at a junction to my left pulled right out in front of me. Bounced over him, landed well and got away with a graze. Alas not the bike though - mangled frame. Cost the company whose van it was a new bike.
Next one... Don't remember it. Have no clear idea what happened. I'd been wearing a helmet, which clearly didn't help when I hit the road chin first. I assume it was chin first, as thats where the wound was. Broke a tooth, cracked an eye socket, stitches on lip and chin, bruised leg and hip and a nasty shiner that came up over the next too days. No idea what happened; the one witness was the car that had been on the road behind me, a taxi, who was adamant he was nowhere near me.
Third one... I moved to the side of the road at lights and put my leg out to balance on the kerb. Turned out that the kerb was slippery, I slipped, fell over, and dislocated a couple of ribs when I landed chest first on a railing. Gosh, but that was painful.
Lots of near misses and mostly harmless tumbles; I've ended up in the River Trent once when on a mountain bike (the bike stopped, the shingle under it didn't). Ended up tumbling off mountain bikes many times actually, but mountain biking can be like that. Came off a few other times, never been hurt properly thogh.