Yea, I also always create my own "bosses". Actually I do for most monsters I use. For the boss encounters themselves though, I try not to just make it about beating on the villain himself but about the settings and/or the resources he has. Usually, for setting, I'll try to have a very detailed battleground, with a lot of things potentially happening and lots of player options. If the boss fight is meant to be climatic, then I want crazy shit to happen everywhere. For resources, it depends on the villain. That can range from tons of minions potentially harassing the PCs, magical trinkets, even god interventions and whatnot. But you asked for ideas, here's what I call "pulling an Indiana Jones" :) 1) Have the PCs go through some kind of crazy gauntlet run to reach the villain. Maybe bash through tons of minions, avoid a trapped maze with time pressure, building on fire about to crumble, anything that puts tension, time limit and really push players to go beyond what they think they can do. Go crazy but keep the villain out of it all completely for now. Making time important is good here usually because that unsettles the "routine" players tend to get into during combats and other encounters. 2) Finally the PCs reach the villain, probably wounded, out of resources, and worried to death because they now need to fight that big bad. It's mano a mano, Party VS the Big Bad. Game on, let's do this! He's bathed in deathly power, maybe he just finished that crazy ritual, glowing with necrotic magic, resplendent in his villainy.... ...and then the PCs one-hit kill him, first attack of the first PC cuts him right down the middle....he stumbles..."but...how..." and dies... Then you just find whatever reason you want (maybe the whole process drained him, maybe he did it wrong, maybe the demon he kept under control to do his bidding finally decided to end this, maybe one of his apprentices betrayed him and poisoned him a couple days ago, whatever!). That's what I call an "Indiana Jones" (big dude waving crazy sword around, killed nonchalantly with a gun shot). Of course, you can only pull that one ONCE per group of players but if done right, it's gonna be a moment they'll remember for a long time :)