- Cassiopeia was designed by Brackhar .
- Brackhar's goal was to create a character in the same flavor as Anivia, but to make a fast sustained damage character as opposed to a slow, bursty one.
- Cassiopeia is voiced by Karen Strassman, Who also voices Fiora, Shyvana, Zyra, and Elise.
- Cassiopeia was the last champion released in 2010.
- Cassiopeia is the third champion to have an Art Spotlight. She features a unique Spotlight, showing the animation process of her taunt.
- Cassiopeia generally has an "Ancient Greece" theme, as indicated with her name and appearance in two of her skins (Classic and Siren).
- Cassiopeia is the third champion, after 20px Gentleman Cho'Gath and 20px Corporate Mundo, to take part in an interview.
- Cassiopeia and Katarina are one of the five pairs of sibling champions. (The other siblings champions include Kayle and Morgana, Garen and Lux, Nasus and Renekton, Darius and Draven)
- Katarina's quote about Cassiopeia is a direct reference to Lady Macbeth's description of how Macbeth should be: "...look like the innocent flower, but be the serpent under't" (I.v.65-66).
- Cassiopeia is a constellation in the northern sky, listed by the 2nd century Greek astronomer Ptolemy.
- The symbolic meaning of the constellation Cassiopeia is "Seated Queen", further referenced by her classic skin.
- Her ability Miasma may refer to Greek mythology, where miasma is a contagious power that has an independent life of its own. Until purged by the sacrificial death of the wrongdoer, society would be chronically infected by catastrophe.
- Cassiopeia is the first champion to currently have a difficulty rating of 100, the second being Orianna.
- Cassiopeia is heavily based on Medusa, a Gorgon from Greek mythology.
- They both were beauties before they got turned into monsters.
- They both have relations with snakes. Cassiopeia being half-snake half-human and Medusa having snake hair.
- Cassiopeia's ultimate, Petrifying Gaze, turns enemy champions into stone, similar to how Medusa's glance turned her enemies into stone.
- Cassiopeia bears resemblance to a combination of a naga, dracaenae, or snake woman, and Medusa.
- Cassiopeia may be a reference to Queen Cassiopeia from Greek mythology who boasted of her great beauty. Poseidon punished her by demanding her daughter Andromeda be sacrificed to the Kraken. Perseus, having just slain the Gorgon Medusa, slew the sea monster and saved the princess.
- Cassiopeia might also be a reference to Cleopatra VII, the last pharaoh of Ancient Egypt. Cleopatra VII was a temptress who seduced various powerful men like Julius Caesar. She killed herself using a bite from an asp.
- There's an interesting link between Cassiopeia and summer version of Summoner's Rift - whenever Cassiopeia is present on it, the snakes (normally randomly appearing doodad-creatures in the bushes) don't appear on the map. It also means that Cassiopeia is the first champion to actually affect the appearance of a map during the whole match.
- Cassiopeia's dance is the "Weeping Willow" dance, a style of liquid dancing.
- Cassiopeia is the only Champion currently able to utilize the effects of other Champion's abilities. 提莫的 Toxic Shot and Noxious Trap, and 辛吉德的Poison Trail Poison Trail can be used to shorten Twin Fang cooldown.
- Cassiopeia's line, "You found me beautiful, once." may be a reference to the movie Army of Darkness, where the female lead proclaims the same to Ash, the male lead, after she is corrupted by the evil Deadites.
- Cassiopeia's picking speech refer to same words of Lady Deathstrike in "X-Men The Animated Series", when Wolverine asks what has she done to herself and she reply same as Cassiopeia.
- Cassiopeia's taunt, "Let me help shuffle off your mortal coil." is a reference to Hamlet, from the titular character's famous "To be, or not to be" monologue.
- Cassiopeia's alternate taunt "You think I'm a freak; let me get on your level" is a tribute to Rioter Phreak's line "Get on my level."
- Her Siren skin is a reference to the mythological creatures of Ancient Greece called Sirens, seductresses that enchanted men into the sea to drown.
- In Perseus Pantheon's skin, Cassiopeia's head is depicted on his shield, most likely referencing their shared Greek relations. From the pose, Pantheon is reflecting 卡西奥佩娅的 Petrifying Gaze, mirroring the Perseus vs Medusa fight of Greek mythology.
- Mythic Cassiopeia is a commemorative skin created to celebrate the launch of League of Legend's Greek servers.
- Cassiopeia is Katarina's younger sister, as well as the youngest member of the Du Couteau family.