Mr Tulip (other names unknown) is, along with Mr Pin, a member of the New Firm, a duo of interloping criminals in the The Truth. He is something of a contradiction: a remorseless killer with the refined soul of a true fine-art connoisseur., albeit works of art he would like to steal. He is differentiated from a common criminal by his habit of removing works of art from houses before committing arson, the ability to distinguish between priceless works of art and common forgeries, and an encyclopaedic knowledge of hundreds of years of great artists, artisans and their works. He is the muscle of the New Firm, and though an instinctive killer, recognises Mr Pin's cognitive skills, and leaves the thinking to him. He also suffers a mild speech impediment, causing him to often insert "—ing" mid-sentence (the suffix of an action verb without the verb itself). This hints that Mr Tulip's parental figures have left a lasting impression on his psyche, as he is someone who WANTS to swear but has been taught not to. It is also likely a commentary on the use and censorship of the swear "f***ing" in dialogue.
One major problem with Mr Tulip is not that he has a drug habit as such, but that he WANTS to have a drug habit, and has a tendency to buy and consume anything sold in little brown bags. Unfortunately he also has the ability to unerringly buy from the one man selling oven cleaner or chalk dust amid an entire city filled with purveyors of illicit narcotics, hallucinogens and stimulants. His primary skill in the New Firm is his apparently unlimited supply of anger, and that he has turned mindless violence into an art form.
Mr Tulip's past is hinted at being dark and fearful, a place even Mr Tulip is afraid to remember, but one of the memories he does have of his youth is the belief that as long as you have a potato, you'll be okay when you die. There are some hints that his family suffered from famine and he overheard that if there are potatoes to eat, the situation is not hopeless. His belief in this is quite firm, as "since they've believed it for centuries, it must be right". He is killed by Mr Pin near the end of the novel and used for a life raft as molten lead flows around the pair. Unfortunately, Mr Pin also steals his potato shortly before killing him, but Mr Tulip manages to retain the memory of a potato in the afterlife and Death allows him to reincarnate as a woodworm: the only woodworm to think 'this is —ing good wood!'