- Kayn is one of 18 champions without a single ability power ratio on any ability: , , , , , , , , , , , , , , , , , .
- He is the seventh dark-themed Ionian-affiliated champion (albeit Noxian-born), after , , , , & ; as well as the second-known member from the Order of Shadow.
- His given name Shieda is pronounced /ˈʃi:da/, and is Ionian in origin.
- His stint as a child-soldier references
- Not all Noxian commanders condone their colleagues' callousness, though they at least turn a blind eye.
- While in Darkin form, the Kayn's ability tooltips change to read "Rhaast" instead of "Kayn".
- His dance references the Reebok dance.
- If you are tied in orbs for  , you will be defaulted to .
- Although patch V7.16 made it so the portrait of the selected skin would be used in the central portion of the in-game UI, transforming into or always uses their base portraits for all skins.
- Kayn is voiced by .
- Rhaast is voiced by Sam A. Mowry.
- Blood splatters from Kayn’s weapon started as water splatters in Riot’s campus showers.
- During development, he was called Nemesis.
- He was originally supposed to be the Nemesis to and
- Kayn is around 20 years old.
- He was 'no more than 10' when Shadow Order. had taken him in into the
- Rhaast is between 3496 and 4396 years old.
- The blue streak in Kayn's hair is the result of using Rhaast. 
- "Zed's dead baby, Zed's dead." quotes . Rhaast:
- "And then there were four? I think." is a reference to an old minstrel song which was made famous in Agatha Christie's "And Then There Were None"*, which counts down 10 children dying one by one. After the sixth child dies, four remain, hence "and then there were four".
- His appearance was inspired by
from the manga and anime series .
- The method in which Darkin possess human bodies is similar to how Demons possess humans in Devilman. Humans in both instances can also overpower the demon/darkin and use their power as their own.
- His appearance pays homage to both
and from , with Vergil's color scheme and Dante's casual & confident attitude that he can subdue any demonic weapon to his will.
- Meanwhile, resembles Dante's reddish forms.
- Other influences are various scythe-wielders in video games.
- Kayn may be a possible reference to Darkin inside Kayn and , a inside Ling Yao). Moreover, Kayn shares quite a lot of similarities in character design with Ling Yao. , a character from the anime . Both characters share similarities in that a superhuman entity reside in them which vies for control of their bodies (Rhaast, a
- Kayn could also similar to , a character from the anime (An adaptation of of the same name). Both wield weapons that are sentient in nature and try to take control of their bodies (Kayn's Scythe contains Rhaast, and Masane's contains an unnamed entity), as well as both of them possessing supernatural powers.
- This skin shares the 'Soulhunter' theme with:
- The Shadow Assassin form seems to reference the from .
- Alternatively the long white hair, red cloak with a tricorne hat and the spell book clasped to his waist could serve as a reference to Final Fantasy's .
- In the Russian localization, he is called 'Showerhunter Kayn' due to a naming error.
- This skin shares the Odyssey theme with:
- Kayn is a big fan of music.
- The hairstyle resemble the villain Jean-Baptiste Emanuel Zorg in
, and his face to in .
- Both and , have the same yellow eyes and body marks because of the Ora in their body. They respectively reference and from the movie .
- The skin is the boss for the Odyssey: Extraction game mode.
- The music that plays during his dance is a remix of Mass Effect's Uncharted Worlds.
- , who currently resides in the Odyssey universe, originally hails from the Event Horizon universe.
- This skin shares the Event Horizon theme with:
- wants to collect Ora to reopen the Ora Gate. Then, he can return to his world. 
- Shadow Order after Zed and the other order members stumbled upon Kayn during the Noxian invasion of Ionia.
was raised by in the
- He is also Zed's favourite pupil and was chosen by Zed himself to be the next Shadow Order's leader should something happen to him.
- Kayn, Zed and some members of the Shadow Order were attacked by .
- Kayn may have a crush on
- knows Kayn and finds him hot but too crazy for her taste.
- ↑ Naming New Champions
- ↑ A. Murtonen, Hebrew in Its West Semitic Setting, Part I, p. 375
- ↑ Agmon, N. Materials and Languages, p. 38-39
- ↑ University of Wales, English - ProtoCeltic wordlist, p. 44
- ↑ Rovient on Kayn Orb Ties
- ↑ The Stories Behind Leagues SFX
- ↑ Ask Riot
- ↑ 
- ↑ /DEV: KAYN AND THE SHOWERHUNTER
- ↑ K/DA Ahri and Odyssey Kayn
- ↑ Rhaast is not from the Odyssey universe
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