Squadmates are NPC's that can be hired to assist the player in Arena Combat, both standard and zombie modes. They can be very useful if properly equipped. The player can equip their squadmates with weapons and armor, but you are unable to change the armor of the special squadmates (see below). Mercenaries costs can range as low as $100, and reaching costs of as much as $4,500. At the 'Hire Merc' screen, the name of the mercenary, level, and primary skill will be displayed. After being hired, mercenaries will become the player's squadmates and have the capability to level up based on the number of kills they get. The player has no control over which stats get raised.
The player decides when/which squadmates to bring into waves. They can also be equipped with weapons and armor but some are unique and cannot. During a wave, squadmates will be signified with a green belt. If they die, they will be removed from the player's roster. There is no limit to how many mercenaries can be hired, but the player can only use up to 6 squadmates in a single wave with maximum Leadership.
Squadmate stats are randomly chosen, as well as their names and gear. This means that after a squadmate dies, the stats will be different if rehired. However, the level that each squadmate is hired at is fixed. Also, squadmate stats do not necessarily correspond with their level. For example, Hank may be at level thirty but his stats can be almost maxed out.
Squadmates arrange their stats upon leveling up based on the player's behavior. For example, if the player dashes and dodges a lot, squadmates will add to their dexterity; if bullet time is used a lot, squadmates will add to their awareness; if pistols are used a lot, squadmate will add to their pistol skill. Squadmates also tend to add to their primary skill. However, squadmates will act the same regardless of their stats.
A glitch occurs in which squadmates can sometimes get stuck in Arena Mode. One scenario is when they do the walking animation but don't move. This happens if you kill the enemies they are targeting too often. Another version is when they stay still and constantly switch weapons. This happens if they have a melee weapon and a ranged weapon and enemies constantly go in and out of their melee range.
There are several special mercenaries that can be hired. Many of them have stats higher than that of other mercenaries and the player in relationship to level. Below is a list of special mercenaries and their hiring levels:
- According to The-Swain, Blockhead was one of the first characters added during the testing phase of the game. He was originally intended to be a character that could not die. 
- Quite commonly, Squadmates can be recruited with gear they can't usually wear, once the armor is unequipped, the Squadmate cannot re-equip it, unless his endurance skill is increased.