The Constructicons were the first gestalt team in the Transformers toy line, introduced in 1985. There were six Decepticons -- Hook, Long Haul, Scrapper, Scavenger, Mixmaster, and Bonecrusher -- all of equal size and all colored a sort of bright green with purple and black highlights. They were modelled after existing construction vehicles of various types; for years after they were introduced as toys you could continue to see the vehicles they were based on along the sides of American highways, often with the exact same green color.
They combined together to form the giant robot Devastator, and were unique among the gestalts in that there was only one way to assemble them into Devastator. (Later gestalts were designed such that any arm or leg could be interchanged with another.)
Being the first of their kind, the Constructicons got oodles of screen time in the Transformers cartoon, not to mention a big appearance in the first part of "Transformers: The Movie". They continued to be used in the cartoon from time to time, despite the addition of other gestalts like Menasor, Bruticus, and Predaking to the Decepticon lineup. Today, a complete set of Constructicons with all accessories can fetch hundreds of dollars on eBay, more than any other gestalt team save possibly the Predacons.