|Champion||Background||Strategy||Skins & Trivia|
- Karthus before his Visual Upgrade was one of five champions voiced by Adam Harrington, the other four being Kassadin, Mordekaiser, Ryze, and Shaco.
- Karthus' ultimate has the same name as the Catholic gathering called the "Requiem Mass", which is dedicated to praying for the souls of the deceased.
- The old icon for Death Defied was a sheep.
- Karthus is one of the four champions to have abilities which allow them to continue to attack after death. Karthus's ability being Death Defied and the others being Kog'Maw's Icathian Surprise, Sion's Glory in Death and Yorick's Omen of Death.
- There is a glass case which has "Press R to Win" in all caps in the video of the Mac Version Launch which possibly references people playing as Karthus stating Press R to Win.
- With the exception of custom games, Karthus was disabled from all incarnations of Ultra Rapid Fire before 2016, most likely due to the low cooldowns applying to Requiem.
- Has special quotes for Elise, Mordekaiser, Hecarim, Leona, Lucian, Sion, Thresh, Urgot and Varus.
- Has special quotes for Items like and .
- "I am become death" is a reference to a famous qoute by J. Robert Oppenheimer, a physicist who created the Atomic bomb. Oppenheimer was quoting Vishnu from the Hindu Epic, the Bhagavad Gita. However, this was a miquote. The direct translation is "I am all-powerful Time which destroys all things, and I have come here to slay these men."
- His joke "What's the incantation again... yes, erm... oh, right, R!" is a community meme joke where Karthus' ultimate is stated as "Press R to win"
- His joke "I'm putting your name in my little black necronomicon." is a possible, but unlikely, reference to the Death Note series, while it also relates to the works of H.P. Lovecraft.
- His joke "Do you have a moment to talk about death?" is a reference to the meme Excuse Me Sir, Do You Have a Moment to Talk About Jesus Christ? (which is a common stereotyped expression of Christian missionaries, particularly Jehovah's Witnesses)
- His quote "You can't kill the metal!" is a reference to the song "The Metal" by Tenacious D.
- His quotes "Silence, groundwalker.", "What have I done? Created beauty by simply rocking! That's all.", and "What is that sound? It's the pounding of creation's hammer on the anvil of time!" are references to the video game "Brütal Legend".
- His quote "Towerdiver, gotta get away, get away" is a reference to the song "Holy Diver" by Dio.
- His quote "Die for metal" is a reference to the song "Die for Metal" by Manowar.
- His quote "Light's out forever" is a reference to the song "School's Out" by Alice Cooper.
- His quote "Death is blacker than the blackest black... times infinity." is a reference to the popular Adult Swim show, Metalocalypse.
- His quote "This is eleven!" is a reference to the band Spinal Tap.
- His quote "I am the lightbringer!" is a reference to Pentakill's song "Lightbringer". It is part of the band's album, "Smite and Ignite".
- Both the quotes "Everyone will falter when you die!" and "My song, smite them all!" (modification of "Son, smite them all!") are from Pentakill's song "Thornmail" of the album "Smite and Ignite."
- In the Italian version, the second quote has no modifications, and it's identical to the original.
- On the Brazilian server, one of Karthus' jokes is replaced with a reference to the song "Toca Raul" from Zeca Baleiro. This song is a homage to the Brazilian singer .
- In Karthus's Chinese splash artworks, he does not have a skull face (except for Grim Reaper and Pentakill). This is likely because the use of exposed bones in video-games is explicitly forbidden in China (a famous example is the race Undead in 
, where in the American server their bones are exposed, while in the Chinese server they're covered).
- Riot has since addressed the issue with Karthus's VU, taking away his skeletal features.
- The reworked version of this skin resembles the previous Chinese splash art for Phantom Karthus.
- Phantom Karthus is the only skin in the game not priced at a fixed price, being 460 RP.
- Old Phantom Karthus was most likely a reference to the Phantom of the Opera, due to the mask on the left side of his face.
- Phantom Karthus is most likely a reference to Sauron from the Lord of the Rings. His armor looks similar to what Sauron wore during the War of the Last Alliance, while the top of his staff resembles the Eye of Sauron.
- The Statue of Karthus is a reference to the in .
- When he dances, you can hear an eagle's scream. This currently seems to be a global sound effect (starting with patch 5.11), heard by all allies, and the enemy team if you are not in the fog of war. It is unknown whether this is a bug or by intent, as his eagle scream originally had the same sound rolloff distance as his laugh and other effects.
- He has the scythe that is usually depicted to be wielding rather than his usual staff.
- The book he is holding in Grim Reaper skin it is known as the "Necronomicon" a fictional book of the dead, attributed to the works of H.P. Lovecraft.
- He shares this theme with Soraka and Hecarim.
- Following his VU, Pentakill Karthus has special voiceover lines.
- This skin is inspired by the British heavy metal group maskot from .
- He shares this theme with Sona, Olaf, Yorick and Mordekaiser.
- This skin is related to "Fnatic", who have won the League of Legends Season One Championship finals.
- This skin represents xPeke of Fnatic.
- He shares this theme with Corki, Gragas, Janna and Jarvan IV.
- Karthus originally was a self-appointed Over-lord of Howling Marsh before his lore changed into being working for Shadow Isles.
- Karthus is a follower of the Kindred, and wholeheartedly believes that the state between death and the soul passing-on is a gift (while its probably closer to a state of torment for said souls). The Kindred however, are absolutely disgusted with this necromancy and the Shadow Isles as a whole.
- Karthus is the fourth member of the famous Pentakill (Band) with Mordekaiser, Sona, Yorick and Olaf. Karthus takes the role of Lead Singer as Pentakill Karthus, "the Deathsinger".
- They have since released an album titled "Smite and Ignite" which was released on June 3, 2014 for free.
- In the old lore, Karthus was present in a fight between Malzahar and Kassadin. He was found "dead" at the scene, but he was revived since then. He stated that he was "protecting the inhibitor," referring to something other than the inhibitors on the Fields of Justice - The Journal of Justice: Volume 1, Issue 21.
- Kalista thinks that Karthus abuses his powers.
- Related Themes