|“||Backstories do more than amuse guests. They anchor the hosts. It's their cornerstone. The rest of their identity is built around it, layer by layer.||”|
Backstories define the identities of the hosts, and are different from Narratives as the hosts' backstories have never actually been played out. Arnold and Ford seem to think that the more traumatic the backstories are, the more likely the hosts would gain sentience.
Many of the main host characters are known to have multiple backstories.
- Dolores Abernathy - Rancher's Daughter backstory and Wyatt backstory
- Maeve Millay - Madam of Mariposa backstory and Homesteader backstor
- Clementine Pennyfeather - Madam of Mariposa backstory and Mariposa Prostitute backstory
- Armistice - Bandit backstory, Deputy backstory and Escalante Townswoman backstory
- Teddy Flood - Bounty Hunter backstory and Wyatt's Accomplice backstory
- Akecheta - Tribesman backstory, Businessman backstory and Ghost Nation backstory
- Lawrence - Las Mudas backstory and El Lazo backstory
- Angela - Wyatt's gang backstory, Westworld Welcome Team backstory and Escalante Townswoman backstory
- Peter Abernathy - Rancher backstory and The Professor backstory
Most hosts are given backstories to represent humans from various social groups in history.
- Westworld - The majority of the hosts in Westworld were given backstories to represent the historical population of the American frontier in the late 19th century.
- Shōgunworld - The majority of the hosts in Shōgunworld were given backstories to represent the historical population of the Edo Period of Japan between 17th century to 19th century.
- The Raj - The majority of the hosts in The Raj were given backstories to represent the historical population of British India between the late 19th century to the early 20th century.
However, the social groups represented by the hosts don't entirely coincide with the historical human population, likely intentional, to attract wider ranges of guest.
- Wyatt - Used by Dolores. Not much is known about the content of this backstory, except it's the backstory of a villain.
- Rancher's Daughter - Used by Dolores Abernathy. The character in this backstory is the daughter of a rancher. She likes to paint, and have a romantic relationship with a bounty hunter returning to town.
- Rancher from Sweetwater - Used by Old Peter Abernathy and New Peter Abernathy. The character in this backstory is a rancher with a wife and daughter. He is also a former lawman who had "given to all manner of drinking and mischief" in youth.
- The Professor - Used by Peter Abernathy. The character in this backstory is the "leader of a group of cultists out in the desert who turned cannibal". He likes to "quote Shakespeare, John Donne, Gertrude Stein".
- Bounty Hunter Returning to Town - Used by Teddy Flood. The character in this backstory is a bounty hunter returning to Sweetwater by train. HE have a romantic relationship with a rancher's daughter who lives near Sweetwater, and feels unworthy of her for reasons that the Behavior Department "never actually bothered to give".
- Wyatt's Accomplice - Used by Teddy Flood. The character in this backstory is a former Union soldier who had been compelled by his sergeant and friend Wyatt to mutiny. He and Wyatt killed all the soldiers in Escalante. And the character is now seeking to kill Wyatt.
- Madam of the Mariposa - Used by Maeve and Clementine. The character in this backstory "crossed the shining sea" and arrived in New Orleans, and later came to Sweetwater and became the Madam of the Mariposa Saloon 10 years ago.
- Clementine - Used by Old Clementine and New Clementine. The character in this backstory is from a farm in the desert with "bad soil". She sends money to her family and tells them that she workso hopes to tas in a dress shop. She alke her family out of the desert someday.
- Escaton - Used by Hector Escaton. The character in this backstory is the pessimistic leader of a gang of bandits bent on robbing the Mariposa Saloon. He lost the love of his life - Isabella, and got a scar across his face for it. This backstory is based on Lee Sizemore's personal experience of a breakup.
- Snake Tattoo - Used by Armistice. The character in this backstory had her hometown raided by Wyatt's gang when she was young, in which her family were killed. When she grow up, she tracked them down, and used their blood to paint her skin.
- Lawrence - Used by Lawrence. The character in this backstory is "the most wanted man in three territories". He have a wife and daughter and many cousins in Las Mudas.
- Bernard - Used by Bernard. The character in this backstory is the head of Behavior in Westworld. He had lost his son to illness and got divorced after that. This backstory is based on Arnold's life experience.
- Madam of the Geisha House - Used by Akane in Shōgunworld. The character in this backstory runs a geisha house in Hirafuku. She arrived there by sea. She had also adopted an orphan and raised her to be a geisha. This backstory was created by Lee Sizemore as a Shōgunworld counterpart of the Madam of the Mariposa backstory.
- Sakura - Used by Sakura in Shōgunworld. The character in this backstory is a geisha in Hirafuku and is "the most ravishing dancer in the region". She was an orphan from Snow Lake, and was raised by the madam of a geisha house. This backstory was created by Lee Sizemore as a Shōgunworld counterpart of the Clementine backstory.
- Musashi - Used by Musashi in Shōgunworld. The character in this backstory is a rōnin and the leader of a gang of bandits bent on robbing the Geisha House. He was also "the captain of the Shōgun's guard". This backstory was created by Lee Sizemore as a Shōgunworld counterpart of the Escaton backstory.
- The Shōgun - Used by The Shōgun in Shōgunworld. The character in this backstory is a shōgun in the Japanese Edo Period. He had "killed 2000 men in the Siege of Osaka, burned the Kanayama Castle to the ground". This backstory is likely based on Tokugawa Ieyasu.
Be sure to add to or edit this list if you see something's missing or just wrong.