Cain is the last surviving descendant of the original members of the Horadrim, an ancient order of magicians charged with trapping the series' primary antagonists within enchanted crystals and guarding them thereafter.

The character is originally named after the winning entry of a fan contest organized by Blizzard and PC Gamer, and is voiced by Michael Gough for all media.

[1] This was the result of a promotional contest jointly run between Blizzard and PC Gamer in the mid-1990's, which gave fans an opportunity to have their name referenced in the then-upcoming Diablo, and the winning entry was to be drawn by random pick.

[1] The Elder family later received a letter personally written by Diablo producer Bill Roper to congratulate their winning entry, as well as a bundle of gift prizes which included a copy of the game and assorted merchandise.

[5] Another prank by Blizzard Entertainment for April Fool's Day the following year involved the false advertisement of a Deckard Cain GPS voice pack for sale as merchandise.

He eventually reveals to the player character that his ancestor, Jered Cain, is a leader of the Horadrim Order who personally led the party that pursued and captured series antagonist Diablo.

[9] Cain appears in the video game Overwatch as the PA announcer for the Diablo zone of Blizzard World, a virtual theme park filled with attractions and references inspired by various Blizzard-developed intellectual properties.

[2] Joey Thurmond from Game Informer expressed a fondness for Cain and other "wise, scholarly characters in fantasy stories" like him, such as Gandalf or Paarthurnax from Elder Scrolls V: Skyrim.

[13] Earnest Cavalli from The Escapist noted that Cain is one of the "most famous cryptic old men" in video games and that prior to the release of Diablo III, he was the series' only true recurring character.

He compared Cain's behavior to that of Navi in The Legend of Zelda: Ocarina of Time, and claimed that he resented the in-game guide in both games more than any foe he faced.

[16] Tarason noted that a solution presented by Heroes of the Storm is by letting individual players be part of their entire team's shared level progression.

[17] Wesley Yin-Poole from Eurogamer said making Cain a less combat-oriented character has given Blizzard the opportunity to adopt a tongue-in-cheek approach with his dialogue and skills, and regarded some of his abilities to be "nice nods" in relation to the series' lore.

[18] Ali Jones from PCGamesN noted that some series fans have also expressed a preference to see Cain paired with a minor character named Neeve in a romantic relationship.