In his splash art, Yorick stands on a tomb with "MORI" engraved. Mori is Yorick's family's surname, and has meanings relating to death or dying in several languages.
"Memento mori" is a Latin phrase that was mostly used in medieval Europe that means "Remember, thou art mortal". It is the most common phrase that uses the word "mori".
His quote "You will remember Yorick Mori." is a clear reference to the very same phrase.
Yorick is the first champion to be released before his champion spotlight, mainly due to Phreak being delayed on a flight back from Dreamhack in Sweden.
Yorick has one of the most varied skillsets in the game, with an auto-attack modifier, a ground targeted AoE, an enemy targeted instant-cast and an allied targeted instant-cast. Among these are both controllable and incontrollable pets.
Yorick and Shaco are the only champions to have both Automatic and Controllable pets.
The skin changes his dance, as he does not spin his weapon during the dance, but rather lifts his hand up and makes a sign with his hand. (The same hand sign the ghoul makes in his Pentakill splash art.)
Yorick serves as a ferryman for the Shadow Isles's undead denizens, helping them climb death's many-tiered ladder.