There are soooo many videogames, which have them. Do you have your favourite boss? Or a boss memorable in very bad way?
Ps. Obvious spoilers incoming.
The most memorable boss fight for me is from Final Fantasy 8. Its last boss is memorable...in quite bad way. It has four phases where you fight with your every character. If they aren't recorvered when they are K.O'd enough quickly, they disappear and replaced with new character, if possible. That isin't the most annoying thing however.
After the first phase, the boss can destroy your characters' spells. Have fun when it destroys all your recorvery magic. The boss also then loves to spam moves, which deal 1000-5000 damage (Max health is 9999). The boss doubles its health in each phase too. It took about 3 hours to defeat the boss. There was zero fun factor in there...