It has been hinted that Irelia's brother Zelos is possibly being made into a champion and is currently in development.
Irelia, has among the highest potential tenacity stat in the game, capped at 64.9% (40% from her passive, granted at least 3 enemy champions are within her sights, 15% from the Tenacious [[Tenacious|]] mastery and 35% from any tenacity item in the game, i.e. Mercury's Treads after being calculated with diminishing returns). Thus, the duration of almost all crowd control effects in the game can be cut by more than half against Irelia.
Irelia is the focus of a LoL meme "better nerf Irelia", in which Morello determines that a certain champion is currently overpowered, but chooses instead to nerf Irelia, due to his numerous alterations to her skillset.
Ирелия была ослаблена за день до своего релиза потому, что как сказал Морело : "Против нее совершенно невозможно играть".
ricklessabandon stated that Irelia is somewhat similar to a lich, and her weapon acts as her phylactery. 
The naming of her style, "Hiten Style", her backstory, and Xypherous' confirmation show Irelia is based on Kenshin Himura of Rurouni Kenshin.