So far, I've downed the Last Giant, The Pursuer, the Lost Sinner, The Old Dragonslayer, the Dragonrider, the Ruin Sentinels, and the Belfry Gargoyles. Maybe another or two I've forgotten. Right now, I'm working toward killing the Executioner's Chariot. This game is brutal so far, with some moments that feel kind of cheap. But overall it's a great experience so far. I forged the Dragonrider's Halberd with Straid, it's pretty effective when I need to switch to a shield.
 
I've also gone on a sort of helping streak, laying down messages almost everywhere. One of my most rated messages is "Try merchant", in front of the Pharros Mechanism in the building where you find the second Forest of The Giants bonfire. Dunno why that one is rated higher than the one I put down detailing the area below the Belfry Luna Ramparts after the gargoyles. Maybe the Pharros lockstone thing isn't so obvious?