In Hearthstone, each player is represented by a hero. Each hero starts with 30 Health, and if that value is reduced to zero the hero will be destroyed, losing the game. Each hero represents one of the 9 classes, determining which class specific cards can be put into the deck, and also comes with its own hero power, a special ability which further defines the play style of that class. Each hero is also a major character from the Warcraft universe, and has their own portrait and emotes.
Players can choose which hero to play, and create custom decks for each class. Players currently begin the game with Jaina Proudmoore (Mage) and can unlock the other heroes by defeating them in Play or Practice mode.
Heroes by default do not have an Attack value, but can use various means to gain Attack, or equip weapons. Heroes with an Attack value can attack other targets, similarly to minions, and will take damage from targets they attack accordingly.
Each hero begins at level 1, and can gain levels through earning sufficient experience (XP). Heroes can reach a maximum of level 60. XP is gained through winning games in any game mode. Winning games against real players awards bonus XP.
Up to level 10, reaching every other level with a hero will unlock a pair of new basic class cards. Above level 10, golden versions of existing class and neutral cards are granted upon reaching certain levels. Raising your first class to level 10 also completes the hidden "Level Up" quest, awarding the player one card pack. Experience and level do not affect gameplay in any other way, and are therefore only truly significant up to level 10.
Currently, there are 9 different heroes to choose from. For a comparison and overview of the classes, and the strengths and abilities of each hero, see class.
- Malfurion Stormrage (Druid)
- Rexxar (Hunter)
- Jaina Proudmoore (Mage)
- Uther the Lightbringer (Paladin)
- Anduin Wrynn (Priest)
- Valeera Sanguinar (Rogue)
- Thrall (Shaman)
- Gul'dan (Warlock)
- Garrosh Hellscream (Warrior)
Playing the warlock card Lord Jaraxxus destroys the warlock and replaces him with the Lord Jaraxxus hero. The new hero is still under the control of the player, but has its own portrait, emotes and hero power. However, Jaraxxus cannot be selected as a regular hero, and any experience gained from playing as Jaraxxus will be given to the player's warlock.
A special selection of heroes are available to battle during the game's introductory tutorial. Each has their own portrait and a selection of story-based dialogue. Many also feature unique hero powers. These heroes cannot be chosen by players, and are not encountered in the rest of the game. Note that although many of these characters also feature as playable minion cards, there is no connection between the heroes and the minion cards.
Bosses are computer opponents found in adventure mode encounters. Each boss is a hero with its own unique cards and hero powers, designed to be "tough, unique, and interesting" encounters that introduce new strategic elements, forcing you to "change how you play".
The following bosses have been announced as part of the planned Curse of Naxxramas adventure:
 Golden heroes
Whenever a player completes 500 wins in Ranked Play mode with a given hero, that hero will be permanently replaced with a golden version. These are similar to golden cards, with golden borders and special animations, and will automatically be used instead of the regular version, in Casual and Ranked play, as well as Duels, but will not be used for Arena.
Hero powers and those minions and weapons created by hero powers will also be affected, with full animated golden versions. Specifically, Searing Totem, Wrath of Air Totem, Healing Totem, Stoneclaw Totem, Wicked Knife and Silver Hand Recruit summoned by golden hero powers will be golden.
Players can track their wins progress with each hero on the Ranked deck selection screen, with the number of wins out of 500 listed beneath the currently selected hero's portrait. Wins from before the introduction of the golden heroes feature do not count toward golden heroes.
 In development
 Alternate heroes
 Patch changes
- Patch 126.96.36.19944
- Golden Heroes have been added and now can be unlocked after winning 500 Ranked games with a Hero! Track your progress on the deck selection screen in Ranked Mode.
- Unlocking a hero now plays that Hero’s emote. Well met!
- Patch 188.8.131.5290 - The maximum level is now 60, and you can earn XP in any game mode up to max level.
- JR Cook (2014-04-13). Interview with Eric Dodds and Jason Chayes, PAX East 2014.
- Jesse Cox (2014-04-11). Twitter / JesseCox. Retrieved on 2014-04-12.
- Hearthpwn: Fireside Chat - BlizzCon Panel
- HearthPwn.com - Golden Heroes Coming Soon! (2014-03-06)
- HearthPwn.com - Golden heroes coming soon (2014-03-06)]
- Facebook - Hearthstone
- Buffed.de: Hearthstone: Alternative Helden-Figuren, Legendaries und Abenteuer - Entwickler im Gespräch (Google Translate)
- Dev Interview: New Heroes, Gameboards, Adventure Mode; Legends of Hearthstone BS2W2