Boss battles are some of the most interesting fights we see in this series. I decided to do a ranking of bosses on my own. This is based on design, power and story behind the boss, so I hope you enjoy this list!

5. Thrym

Even though he doesn’t seem like such a big threat compared to others, considering that he is an ALO boss so he can’t damage the player’s real body, I think he deserves to be on this list.

The story of the quest and the references based on Norse Mythology are really interesting and make you look into the original story (if you don’t know about it already) and learn new things! The quest was also an important one for the ALO universe, if our heroes wouldn’t have beaten him then the game could’ve changed forever.


4. The Fatal Scythe

Even though he can be found in a hidden dungeon on the first floor of Aincrad, don’t let that fool you! You need very high levels to stand a chance against him. Even Kirito and Asuna, who has level way above many others, had troubles facing him. Actually, this boss is the one that could’ve ended their life if it weren’t for Yui who came to the rescue. His strength and surprise effect made me place him 4th in this top.


3. The Skull Reaper

Based on the 75th floor of Aincrad, this was one of the most difficult SAO bosses. When the troops fought it, they ended up having 14 casualties. He has 5 health bars, which is more than the other bosses, who usually have 4 or 3. His attacks are very fast and can kill a target with a single blow. To make things even scarier, he stays on the ceiling before players enter and then just drops in front of them. Yikes.


2. An Incarnation of the Radius

This boss appears in the Sword Art Online: Ordinal Scale movie. It is situated in the Ruby Palace and it was supposed to be the original boss of Aincrad. That fact alone indicates how strong it is. It has way more HP bars than other bosses (which usually have around 4) and a protective barrier that needs to be taken down first. No wonder that Yui had to call everyone she knew from ALO in order to beat this boss. I must add, the design is gorgeous though.

An Incarnation of the Radius, full body.


1. Heathcliff

No surprise that the creator of SAO himself, Kayaba Akihiko is number one on this list. Under the username of “Heathcliff” he lead the strongest guild, Knights of the Blood Oath, and on the 95th floor he was supposed to reveal himself as the final boss. However his surprise was ruined by Kirito, who realised his true identity. The plot twist behind him is what makes him the most interesting boss, even thought he looks like a normal player and not some gigantic monster with many health bars. Despite everything he has done he was fair in the end and rewarded Kirito and Asuna for beating him and his game by not taking their real lives. However, he didn’t give up on his life completely. Since his mind is still somewhere, can we stay that he got defeated for real?

Healthcliff’s death in game.