That's the thing though, Action RPGs and Action games in general can get overly theatrical with the bosses. That's one of the main draws of the genre after all. Giant bosses and over-the-top fights can easily mask the script, kind of like orchestral music can mask a bad composer with its reliance on timbres and effects. If you take a step back you will see the artificiality of them. There is no strategy involved in ARPGs (not top-down Diablo style ARPGs, but Dark Souls style) and Action games, not really. Bosses there are puppets with the same attack patterns repeated over and over again. Some bosses can get fancy with 2 or 3 stages, but it's pretty much the same. RPG bosses can at least vary a little even with basic AI changing the boss' behavior in tandem with the player's actions. They can because the players have a lot of tools at their disposal and is feasible to expect players to use them. I tend to remember these bosses a lot more than in Action RPGs. The only ones from the top of my head are the sewer dragon (forgot the name), spider lady (same) and Capra Demon (cheap) from Dark Souls. From RPGs there are a lot. From BG2 - Firkraag, Yaga-Shura, Kangaxx, Demogorgon, Balthazar, all the dragons, Melissan, I can go on. I actually remember all the bosses around Cyseal, but I can't recall their names. Blob monster, giant crab, failed robot, evil sorceress, big bad under church, skeletal family etc. Diablo 2 - Blood Raven, Countess, THE Smith, Andariel, Radament, Summoner, Duriel, act 3 gets a bit fuzzy, but the Council and Mephisto, Izual, Diablo, act 5 no idea except Baal.
Do you know why I remember these bosses? Because of the context. Either they were so masterfully presented (lore, build up, set up, atmosphere, aesthetics etc.) or just fighting them ingrains them in my memory. Using all the tools at my disposal to overcome them. Do you know what I don't remember? Random mooks with no names. That's actually a jab at the people who suggested D:OS 2 not have any bosses. But it's also true. You can have a council-like fight instead of a single boss sometimes, and that would be great, but not having any bosses would remove the climactic points. Bosses don't only serve a gameplay function, but also an artistic one. If set up right they serve as focal points and add local climaxes which help with the pace of the game. You've all studied literature at one point and I'm sure your teachers have said something about narrative pacing and the wave-like tension it creates with downward and upward motion. That is how you keep the reader/watcher/player's attention and is a sign of good writing. That's the other main reason bosses exist in the first place apart from being a final exam.
I don't remember the names in D:OS because they were neither set up properly nor were they challenging. I remember their concepts because they were actually quite creative and fun with great memorable twists in them. That's not enough though, at least for me. MMO bosses are a completely different beast because the whole situation is different, the inclusion of other people is a critical element. You CAN draw inspiration from them, but you have to be able to extract the meaningful parts that can be used in a single player game and filter the garbage. Using the environment can add a different twist to a boss, sure, but with moderation.
