Characters are representations of people, creatures and mechanical creations within Hearthstone. A character may be a minion or a hero. Each character has an Attack and a Health value, and can attack other characters. If its Health reaches zero, the character is destroyed.
Heroes
- Main article: Hero
Heroes represent the players in each battle. If a player's hero is destroyed, that player has lost the game. Each hero belongs to a different class, each with its own cards and hero power.
Minions
- Main article: Minion
Minions are characters that are summoned onto the battlefield to fight for their hero. Minions are controlled by the player who summoned them, and can be commanded to attack their opponent's minions, or even the opposing hero. Minions with Taunt can act as tanks, preventing the opponent's forces from attacking the hero directly with melee attacks until that minion is destroyed. Minions are a major element in battles between heroes, and are usually responsible for the majority of all damage dealt in a game.
Combat
Each turn, any character with at least 1 Attack can choose to attack an enemy target of their choice. Characters with 0 Attack cannot be used to attack. While most minions have an Attack value of at least 1, heroes by default have no Attack value. However, heroes can equip weapons, granting them the Attack value and abilities of the weapon; effects such as 
Shapeshift can also be used to grant the hero bonus Attack. Each time a hero attacks with a weapon equipped, that weapon will have its Durability value reduced by 1, and when its Durability reaches zero the weapon will be destroyed.
Attacking exhausts a character, preventing it from attacking again until next turn. Minions enter the battlefield in a state of exhaustion, unless they have the Charge ability. Windfury allows a character to attack twice before becoming exhausted. Freeze effects can freeze a character in place, preventing them from attacking next turn.
When attacking, the controlling player selects a character and directs it to attack an enemy target of their choice. However, minions with Taunt must be attacked before other targets. If there is more than one enemy Taunt on the battlefield, the player may choose which to attack.
Combat causes each character to immediately deal damage to the other, simultaneously. If either character's Health reaches zero, they will be destroyed, and both participating characters can be simultaneously destroyed in this way.
Heroes
The main source of Attack for heroes are weapons. Weapons are also the only persistent source of hero Attack; all other sources are lost at the end of the turn. However, weapons are only active during the possessing hero's turn, and therefore will not deal damage if the hero is attacked during the opponent's turn. Heroes are generally only attacked during the opponent's turn, but can sometimes be attacked during their own turn, such as through Misdirection, in which case their Attack will be dealt as damage as normal, but no Durability will be lost.
The result of this is that minions can as a rule attack heroes without taking damage; only if accidentally attacking their own hero is it possible for a minion to directly take damage from the hero it is attacking. Heroes will however always take damage as appropriate when attacking minions.
This dynamic is strategically significant: players are able to send their minions to attack the enemy hero time and again without losing their minions in the process; while weapon-bearing heroes are able to whittle down the opponent's forces, but have a price to pay for this utility.