Vroomfondel is a philosopher. He appears in chapter 25 of The Hitchhiker's Guide to the Galaxy, along with his collegue Majikthise, as a representative of the Amalgamated Union of Philosophers, Sages, Luminaries and Other Thinking Persons (AUPSLOTP; the BBC TV version inserts 'Professional' before 'Thinking'). The Union is protesting about Deep Thought, the computer which is being asked to determine the Answer to the Ultimate Question of Life, the Universe and Everything.
Vroomfondel and Majikthise maintain that the search for ultimate truth is 'the inalienable prerogative of your working thinkers' (Majikthise), demand rigidly defined areas of doubt and uncertainty (Vroomfondel), and consequently insist that Deep Thought be shut down. At one point Vroomfondel (in an agitated state) even demands that his name is Vroomfondel. However, Deep Thought persuades the philosophers that they can 'keep themselves on the gravy train for life' by arguing in public about what answer the computer will eventually give.
Pawlak, Alexander and Joll, Nicholas, 'The Funniest of All Improbable Worlds - Hitchhiker's as Philosophical Satire' in Joll, Nicholas (ed.) Philosophy and The Hitchhiker's Guide to the Galaxy (Palgrave Macmillan, 2012).