His passive, True Grit, is a reference to a book and two movie adaptations (One in 1969 and the other in 2010) by the same name.
Graves was mentioned in the Journal of Justice: Issue 29, where he reportedly escaped from a secret prison owned by CEO Dr. Priggs, who is later seen held at gunpoint in Graves' teaser.
Graves' ex-partner, Twisted Fate, sold Graves out to Dr. Priggs in exchange for entry into the experiment that gave Twisted Fate the ability to use magic.
Graves named his shotgun "Destiny", which is the name of Twisted Fate's ultimate.
Graves' jokes are related to gallows humor, or humor that involve being funny in the face of, and in response to, a perfectly hopeless situation.
Graves' dance references from the cowboy dance during a country show. A direct side-by-side comparison can be seen here.
Graves is the second-last champion to have a League Judgement; the feature was discontinued after his release, but Varus received a Judgement as part of his promotional material by Penny Arcade.
When Graves is about to crit, his weapon has extra recoil making his gun shoot up into the air out of his left hand.
The poncho Graves wears in his classic version is likely a reference to the "Man with no name"; an iconic movie hero appearing in a trilogy of classic spaghetti westerns ("The Good, the Bad and the Ugly" being the most notable).
If an enemy Nocturne is hit by his Smokescreen, Graves will say "I've got your darkness." or "Who's in the dark now?".
Graves' quote "I ain't got time to bleed." is a direct reference to the movie Predator .
Graves' quote "Dead man walkin." is a reference to the prison slang used for a prisoner's last walk to the execution chamber.
Graves' quote "Feelin' lucky?" is probably a homage to Clint Eastwood, the actor who portrayed the aforementioned hero. The line "Do you feel lucky, punk? Well do ya?" is Clint Eastwood's most famous line.
In Polish client, after using Smokescreen, he say "Ciemność widzę" (I see darkness), which is reference to "Seksmisja" from 1983. Also his joke "Zawsze sikasz przez zapięty rozporek?" (You always pee with slit closed?) is from movie Kiler. The interesting thing is, both quotes are said by Jerzy Stuhr.
Also his quote "W imię zasad" (In the name of the rules) and "Co Ty wiesz o zabijaniu?" (What do you know about killing people?) is a reference to Franz Maurer from the movie Psy from 1992. Both quotes are known to be said by Bogusław Linda.
The playing cards in Graves' classic splash art have Twisted Fate's face on them.
Hired Gun Graves skin has a bear paw on his back, which can be a possible reference to Blackwater, a US military contractor. It also seems to be a reference to the game Duke Nukem.