John Cleese

Context: Along with Gilliam's animations, Cleese's work with Graham Chapman provided Python with its darkest and angriest moments, and many of his characters display the seething suppressed rage that later characterised his portrayal of Basil Fawlty.  Unlike Palin and Jones, Cleese and Chapman wrote together in the same room; Cleese claims that their writing partnership involved Cleese doing most of the work, while Chapman sat back, not speaking for long periods before suddenly coming out with an idea that often elevated the sketch to a new level. A classic example of this is the "Dead Parrot sketch", envisaged by Cleese as a satire on poor customer service, which was originally to have involved a broken toaster and later a broken car (this version was actually performed and broadcast on the pre-Python special How to Irritate People). It was Chapman's suggestion to change the faulty item into a dead parrot, and he also suggested that the parrot be specifically a "Norwegian Blue", giving the sketch a surreal air which made it far more memorable.  Their humour often involved ordinary people in ordinary situations behaving absurdly for no obvious reason. Like Chapman, Cleese's poker face, clipped middle class accent, and intimidating height allowed him to appear convincingly as a variety of authority figures, such as policemen, detectives, Nazi officers or government officials--which he would then proceed to undermine. Most famously, in the "Ministry of Silly Walks" sketch (actually written by Palin and Jones), Cleese exploits his stature as the crane-legged civil servant performing a grotesquely elaborate walk to his office.  Chapman and Cleese also specialised in sketches where two characters would conduct highly articulate arguments over completely arbitrary subjects, such as in the "cheese shop", the "dead parrot" sketch and "Argument Clinic", where Cleese plays a stone-faced bureaucrat employed to sit behind a desk and engage people in pointless, trivial bickering. All of these roles were opposite Palin (who Cleese often claims is his favourite Python to work with)--the comic contrast between the towering Cleese's crazed aggression and the shorter Palin's shuffling inoffensiveness is a common feature in the series. Occasionally, the typical Cleese-Palin dynamic is reversed, as in "Fish Licence", wherein Palin plays the bureaucrat with whom Cleese is trying to work.  Though the programme lasted four series, by the start of series 3, Cleese was growing tired of dealing with Chapman's alcoholism. He felt, too, that the show's scripts had declined in quality. For these reasons, he became restless and decided to move on. Though he stayed for the third series, he officially left the group before the fourth season. Despite this, he remained friendly with the group, and all six began writing Monty Python and the Holy Grail; Cleese received a credit on three episodes of the fourth series which used material from these sessions, though he was officially unconnected with the fourth series. Cleese returned to the troupe to co-write and co-star in the Monty Python films Monty Python and the Holy Grail, Monty Python's Life of Brian and Monty Python's The Meaning of Life, and participated in various live performances over the years. CANNOTANSWER

Question: Who was Graham Chapman to John Cleese?
Answer: writing partnership