Who have I always wanted to fight?
Strahd von Zarovich. Preferably the nigh-epic 3.0 version of him that actually had levels in Fighter and Rogue to make him physically imposing as well as magically potent, not to mention the Dark Lord of the Demiplane of Dread.
I joined a Ravenloft campaign specifically to try and make that fight happen, and the DM seemed greatly amused by my character concept and said it would be a fine goal for me to set in his campaign. My character was a Gundarakite Human Fighter going for Holy Liberator. Since the campaign was set during a period where Count Gundar had been "inactive" and Barovia and Invidia were occupying the territory, it made a good deal of sense for some rebel to get it into his head to try and throw out the invaders and re-establish a domestic government. The twist here is that my character had gotten another crazy idea into his head: socialism. I figured that even if I succeeded in ousting Strahd, I could contribute to Ravenloft's overall theme by being backstabbed by my cohort (who would then put my corpse in a glass coffin while he ruled with an iron fist in the name of my revolution). That was Plan B, however. Plan A was always to die fighting Strahd himself, preferably in some dramatic fashion (I actually planned to take that feat from Rokugan where you leave yourself open to a coup de grace in exchange for being able to do the same to your opponent, specifically for the cool image of staking Strahd even as he ran me through).
In the course of two years and some 17+ levels, we visited Borca, Richmieulot (sp?), Falkovnia, Invidia, Barovia, Nova Vasa, Kartakis, Tepest and Keening, meeting most every Dread Lord along the way, and occassionally throwing down with them...except Strahd. The party kept finding excuses to not bother with him at all, despite my very public desire to overthrow him. Since I had the lowest charisma in the group (a 14, but the rest of the group consisted of a Sorceror, a diplomatic Cleric, a Wilder, and a Bard), my vote essentially counted for nothing. So I schleped around the Core being a sack of hitpoints for this group of angsty charisma-based casters, and tried not to complain overmuch that I wasn't getting to advance my plot because of their opposition.
Then it happened, the adventure where we became "enlightened" and realized the true nature of the plane, and of Strahd, and how fundamentally futile it all really was. After that, I couldn't even convince the party to try. Worse yet, the DM thoroughly trashed my character's background by "revealing" that my Gundarakite's mother had been raped by the Darklord of Falkovnia, and that he was my real father. So not only do I not get to fight Strahd, I'm told it's pointless to make the attempt, and then I have my character background altered by a cliche and frankly insulting DM twist. It's like Captain America finding out that his real father is Mousillini; completely out of left-field, and uncalled for.
About that time, I'd had enough of the DM and of the group both in character and out of character. I left the campaign, and they went on to fight some Cthuloid thing in the Shadow Rift and managed to alter the structure of the plane for the better. Apparently my character is still being used (without my consent) as a background NPC in that DM's new Ravenloft campaign, leading a group of Gundarakite rebels against Invidia. However, in my own heart and mind, I know that fueled by his rage at the futility of it all, Sir Mayhew Engels would have walked alone into Castle Ravenloft to meet his destiny rather than accept this mockery of existance.
Robert "Yes, I'm Still Bitter" Ranting