Zilean's concept may be inspired by the fictional personification of time, Father Time, who is usually depicted as an elderly bearded man, dressed in a robe, carrying an hourglass or some other timekeeping device.
Zilean's back story is similar to the book Slaughterhouse-Five by Kurt Vonnegut, Junior.
The main character, Billy Pilgrim, discovers that he randomly jumps between different moments of his life, but is unable to change anything that has happened. He relives his life at random intervals from birth to death for all eternity.
When Zilean is in a match where an enemy Volibear is present, he gets a buff called Armored Bear Hater.
This icon reads: "In my day, we would never have allowed an armored bear into the League of Legends."
Volibear also gains an icon when Zilean is in the opposing team. Allied Volibear is unaffected.
Additionally, if the enemy Volibear kills Zilean, he will remark "I have a special claw for you, Zilean" or "Your time has come, Chronokeeper."
This is a reference to Zileas, who was against the possibility of Armored Bears on the forums.
Zilean's Time Warp has the longest duration of any crowd control effect in the game at 5.5 seconds. Followed by Nasus'sWither which is 5 seconds.
Chrono Shift can cause a gamebreaking bug: if Kog'Maw with Chrono Shift dies, his passive would trigger immediately and then, once again after 4 seconds, dealing up to 1100 overall AoE true damage at level 18.
Zilean is the first champion to have a non-ultimate ability which can not be ranked up at level 1. The ability is Rewind, since Rewind can only be used to reduce other abilities' cooldowns, making the spell useless if ranked at level 1.
Zilean was the first champion to be released after initial release.
Classic Zilean's Chinese splash art is used as the background when you have abandoned a match.
Relations
Zilean joined the League to find a cure for a disease called chrono-displasia, and to save his people.
Zilean constantly consults Ryze, for using summoning magic, similar to magic that summoners use, to find a cure. Ryze stated that they are close to the cure.
It was Zilean who developed the temporal stasis bubble that halted the war in Kalamanda. The high amount of magic used for the bubble also led to the awakening of Skarner.
Due to the fact that the Riot design director, Zileas, was adamantly against the implementation of armored bears, Volibear and Zilean dislike each other.