Mammoth Duncan is a fictitious character from the YouTube comedy series, The Lenny Lego Show. He is one of the main characters of the show, appearing the most often of the anthropomorphic characters of The Lenny Leggo Show.

In 2016, when The Lenny Lego Show was cancelled and replaced with The Lenny Leggo Show, his character was converted into Harvey Duncan.


Mammoth Duncan was an anthropomorphic mammoth. He was widely believed to be the only mammoth left in existence, thus everyone claims that his species is extinct (although technically "critically endangered", if he really was the one remaining mammoth left, he has no breeding grounds and the fate of his species is sealed as "extinct"). Harvey becomes infuriated, and even offended, when someone calls him extinct, as he firmly believes, with his entire heart, that there are indeed other mammoths somewhere, although others merely misinterpret this as a character who doesn't want to face reality. He is dedicated to discovering evidence that Mammoth's are, indeed, not extinct (or about to become extinct). As a result, he has created a company called P.U.F.T.E, Prevent Us From Total Extinction, which is dedicated to scientific research and discover of the existence of additional mammoths.

While nearly every character of The Lenny Lego Show believed that Mammoth's are extinct, it is never made clear on the show whether or not Mammoth's species really is about to go extinct upon his death. Additional episodes will explore the possibility of Mammoth discovering a biological kin somewhere out there in the world.

Mammoth Duncan was apparently adopted; his adopted kin as actually a family of pigs (except for Pigpig, who was fostered when both of his parents died when he was an infant).

Harvey is very short tempered; he is easily angered, and as a result, he is picked fun on constantly. Harvey always throws "Adult" hissy fits when either the slightest of things don't go his way, or when someone is making fun of him; however, this promotes people to make fun of him even further, due to his sheer inability to handle anything as simple as constructive criticism. At P.U.F.T.E, he refuses to let any of his employees show him a better strategy, in terms of research, finance, or anything else. He insists that he knows everything, and that just because he is the organization founder, that he is smarter than anyone else at P.U.F.T.E. When P.U.F.T.E fails to achieve any results in anything, Harvey always blames it on his employees. At P.U.F.T.E, he is very intolerant of any kind of misbehavior, distractions, or slacking off. Harvey is also, rather often, annoyed, even if nothing in particular is ruining his day.

Like Randy Stallone, Mammoth walked on all fours, rather than his hind legs, during this incarnation.