The fist represents the unarmed state for the protagonist; he will not draw attention in weapons-free zones, and merely locking onto pedestrians or police will not cause a panic or attract a Wanted level. However in some GTA games, if you swing your fist near someone, there is a chance he/she might attack you. In some GTA games, fists can be augmented with Brass Knuckles to increase damage.
Naturally, fists are a last-resort weapon in the GTA games, lacking the range of firearms and power of melee weapons. Bare-handed attacks have unique properties - for example, they can be chained, causing the protagonist to unleash a series of various punches and kicks, including a stomp or ground-level kick if an enemy is lying prone. In Grand Theft Auto: San Andreas, the player is able to learn more powerful moves by fighting and defeating gym trainers. Grand Theft Auto: Vice City Stories introduced new abilities while fistfighting, including breaking opponents' necks. In the Grand Theft Auto IV era, fighting was made more realistic, and timing elements were introduced into physical combat to allow dodging and melee counters. While there is almost never a need to fight barehanded in multiplayer, fist fights are often fun, including in GTA IV,
In GTA IV, the player would be able to disarm another person who has a melee weapon and keep it as their own. To do this, the player must first be unarmed and dodge the attack then quickly press the attack (Circle for Playstation and B for Xbox) or counter-attack (Triangle for Playstation and Y for Xbox) button.
In Grand Theft Auto V, as seen in the Micheal trailer, fighting tactics returned from GTA IV but some fighting tactics became a bit more professional looking than Grand Theft Auto IV. In the Michael trailer, Michael is seen hiting a bald man (As seen in the picture in the left) with his fist and elbow. This probably came out of Max Payne 3, another game developed by Rockstar games.
Since the Fist is, technically, a weapon, targeting a cop increases your Wanted Level. Also, targeting a store owner causes them to panic, while targeting drug dealers will force them to attack you, though this is not implemented in GTA IV and its episodes.
Interestingly, fist combos can damage and destroy a car. If you have a maxed-out Muscle in GTA SA, including the Martial Arts combo, a normal car like the Greenwood can be destroyed in less than twenty-five hits. This also works for some lamp posts that can be broken down with a couple of punches. This can also be done in GTA CW.
Destroying car with fists do not attract wanted level, no matter how many cars the player destroys.
The Fist can be chained as a combo with other melee weapons (except the chainsaw) by using Gym Styles and using the melee weapons upon the third strike and vice versa, this technique usually kills a pedestrian after the combo is completed.
In Grand Theft Auto 1 fists are not fatal, the same applies to the Grand Theft Auto London games also. In these games fists are designed to only knock NPC characters over or used to intorrogate them. NPC fists are also non fatal to the player. But using them may still scare away pedestrians or attract police. You can kill with them if they are used as a pushing mechanic to push people into danger however but the actual fists do no damage and a fistfight can last forever if you let it.