Marvel's Dark Tower Almanac describes the can-toi as being the results of human/taheen interspecies mating, and that they tend to exhibit "the most undesirable characteristics of both species". Unlike the taheen, which have the heads of various animals, the can-toi always have the heads of deformed rats.
The can-toi have extremely poor hygiene (many are infested with fleas and lice), and many carry diseases such as rabies. Their teeth are constantly growing, but are worn down by constant chewing.
The can-toi and humansEdit
The can-toi seem to possess an oddly ambivalent attitude toward humankind, both idolizing and mocking its culture at the same time. Their religion states that the can-toi will replace humans once the Dark Tower falls. Because of this, the can-toi wear synthetic human masks, made from a living latex that is grown by them, which they believe is their first step to becoming human. These masks have bleeding red holes on the forehead for breathing purposes, which are described as always welling up but never actually bleeding. These red holes may 'dry up' depending on which world they are in.
Their clothing is garish, usually consisting of vibrant colors and clashing patterns. When "Earthside" they tend to get around by driving replicas of classic American cars. Their cars are strongly hinted at being alive; in one instance a tire extruded a tentacle to snatch at a piece of litter.
The can-toi also have a practice of adopting names from American pop culture once they reach adulthood, with occasionally absurd results. When briefing Roland's ka-tet about them, Ted Brautigan mentioned one named Van Gogh Baez.
The can-toi are described as functioning in two major areas of service for the Crimson King: guards at Devar-Toi and as trackers. Their role as guards at Devar-Toi appears to be mostly in subservience to the Taheen supervisors. As trackers, they seem to be allowed a much longer leash as they direct and carry out missions as varied as the capture (and in the case of Ted Brautigan, the recapture) of new Breakers and the hunting down of enemies of the Crimson King, such as was described in Dark Tower V, through the recollections of Pere Callahan.
The Can-Toi methodology in these seeker/hunter escapades is in-line with their overall absurdist take on human culture. They communicate to their targets via lost pet posters and obscene graffitos.
The 'low men' appeared in the 2001 adaptation of Hearts in Atlantis, and not surprisingly, all the Dark Tower connections were gone. Instead of being agents of the Crimson King sent to kidnap Brautigan for 'breaking' the beams, they were instead members of the government which were "recruiting" psychics to combat Communism.