- Kassadin was designed by Ezreal.
- The icon of Kassadin's Null Sphere is the same used for Exalted with Baron Nashor Exalted with Baron Nashor buff.
- Kassadin is one of five champions voiced by Adam Harrington, the other four being Karthus, Mordekaiser, Ryze, and Shaco,.
- Kassadin's Festival skin was released during the 2010 Winter Olymics.
- Kassadin's Deep One skin is a reference to the Deep Ones, frog-like beings who live underwater in the Cthulhu Mythos.
- Pre-Void Kassadin's robe appears slightly purple in the artwork, but it is actually brown in game.
- This is due to a lighting effect added to display a glow from the void entity in the artwork.
- Kassadin's quest to protect Valoran from the Void gives him a deep enmity towards Voidborns and Void-influenced beings, such as 20px Cho'Gath, 20px Kog'Maw, 20px Kha'Zix and Malzahar.
- According to the Journal of Justice, Kassadin is rumored to have followers called "The Preservers of Valoran". They seek to stop the impending invasion by the creatures of the Void. As such, they are at odds with Malzahar's group, "The Cult of the Void," who seek to unleash the Voidborn onto Valoran.
- Zaunite officials speculate that Kassadin's daughter was captured by Malzahar for a sacrificial ritual. She is now trapped within the Void.
- Kassadin and Malzahar engaged in combat in the mountains outside of the Institute of War and were eventually stopped by League Adjudicators. Karthus was also present at the scene, though for unknown reasons. He stated that he was "protecting the inhibitor," referring to something other than the inhibitors on the Fields of Justice.