Primary Monkeys are the first category of towers in BTD6. They are unlocked at the start of the game. There are 6 Primary Monkeys in the game: the Dart Monkey, Boomerang Monkey, Bomb Shooter, Tack Shooter, Ice Monkey, and Glue Gunner. The common traits shared by all Primary Monkeys is that they form the main tower elements of a typical tower defense game.
Primary Monkeys affect the sacrifice categories for Sun Temple and True Sun God (and by extent, Avatar of the Vengeful Monkey too). Primary Monkeys also gain exclusive benefits to the upgrades Primary Training, Primary Mentoring, and Primary Expertise. Primary Monkeys gain benefits from the Monkey Knowledge "Come On Everybody!" Primary Monkeys can also be placed on the blue emblem on the map Encrypted. On Primary Monkeys Only, a sub-mode on Easy Difficulty, the only available towers to place are all the Primary Monkeys and the selected Hero.