Smokestack

"Smokestack" Jack Kinland, also known as Smokestack is a minor antagonist of the Netflix superhero cartoon Stretch Armstrong and the Flex Fighters. He is the former reining crime boss of Charter City's Old Town as well a former mentor of Malcolm Kane, during his days as a gang leader before mutated by the Stretch Monster with flexarium allowing him to gain the ability to transform and turn into a cloud of and solidify. He voiced by Clancy Brown.

Crime boss of Old Town
Kinland was the leader of the Kinland Crime family based Old Town of Charter City, and ruled the other gangs of the section of the city. At some point he became a mentor Malcolm Kane and Mickey Simmons, and gave both of them a gang their own, the Stickshifts. However, at some Rook Unlimited, a tech company in which turned Charter City into a futuristic metropolis, run by Jonathan Rook began hiring and Kane having grow tired craziness of Old Town went to work for Rook, eventually becoming head of security.

Mutated by Flexarium
When Rook Unlimited security began to take control of public safety, Kinland was eventually arrested and trialed. At his trial he was found guilty of all charges and sentenced to life in Underwood penitentiary with no chance of parole, much to Kinland's fury. As he was being taken away by the bailiffs, Kinland saw Kane, who was present during the trial, and begged his former protege to help him, but Kane just silently stood and watched. However, on his first night in prison Kinland was approached by the Stretch Monster and was offered flexarium by him. Kinland accepted the flexarium and injected it into himself, gaining the ability to transform into a smoke cloud and solidify. Then Kinland quickly used his new powers to escape from prison.