头目（英语：Boss，同义词：老大、老怪，粤语又称大佬、大嘢、大机）指动漫或电子游戏中出场与主角交手的重要角色。动漫中的头目没有正邪之分，富于正气的角色有时也会成为头目。电子游戏中的头目是在电玩游戏和桌上游戏中攻击玩家的非玩家角色（NPC），是游戏中较为高级的一种敌人，可能是怪物的首领，或背景故事中的巨型怪兽、魔王或超级武器等。在电子游戏中，玩家和头目间的战斗则称为BOSS战或头目战（英语：BOSS battle或BOSS fight）。电子游戏中的头目可能出现在游戏故事中高潮的部份，通常是一个关卡中最强的敌人，或作为一个游戏中重要道具或信息的守护者。一些游戏中（尤其RPG游戏），玩家将它打败后便可过关。美国、日本的一些特摄片、电影、电视剧也出现头目的角色。

In video gaming, a boss is a significant computer-controlled enemy. A fight with a boss character is commonly referred to as a boss battle or boss fight. In the United Kingdom, they are informally referred to as a master or last master if it's the final boss of the game. Boss battles are generally seen at the climax of a particular section of the game, usually at the end of a stage or level, or guarding a specific objective, and the boss enemy is generally far stronger than the opponents the player has faced up to that point. A boss enemy is quite often larger in size than other enemies and the player character. Most commonly, bosses are very hard or impossible to defeat without knowing the correct fighting approach. Bosses take strategy and special knowledge to defeat, such as how to attack weak points or avoiding specific attacks.