This research emerges from an observation that Douglas Adams’s Hitch Hiker Series is not merely characterised by light-hearted comedy, but is underpinned by intricate philosophical ideas, especially those of twentieth century Existentialism and the related notion of absurdity. The study also investigates the interlaced functions of Adams’s fantasy and landscapes of alterity. Paradoxically, Adams’s fantastical creatures serve to illuminate the human condition and the follies and monstrosities that lurk at the heart of humanity. Not only does Adams’s fantasy mirror the maladies of twentieth century society, thus serving a satirical function, but it is also a mechanism for constructing meaning in the shape of alternative realities. Concepts related to alterity, such as simulation (Baudrillard), the structure of ‘reality’, dreaming (Descartes) and parallel universes are investigated as building blocks of Adams’s fantastic story space. Furthermore, the ideas of Sartre, Camus and other originators of Existentialism, a philosophy which considers the futility of existence and the compulsion to construct subjective meaning, are elucidated and explored in relation to Adams’s work. Existentialist concepts such as facticity and angst, as well as the Beckettian universe and the Theatre of the Absurd, are also discussed in the light of the Hitch Hiker series. Adams’s extensive satirical comment is also emphasised in this study. Adams’s satire does not merely castigate the evils of twentieth century society such as capitalism and bureaucracy, it also unmasks universal human vices such as pomposity and grandiosity, vices that are rooted in the rejection of objective morality. Although Adams comments on the folly at the heart of society, he also presents the reader with an alternative: the subjective reconstruction of one’s inner world in an attempt to spin individual webs of meaning from the nothingness at the world’s core. This study also investigates the ambiguous concept of madness as a subjective reality born of the necessity to construct meaning, and analyses Adams’s alternative landscapes based on the suggestion that ‘much madness is divinest sense’ (Emily Dickenson, in Ferguson et al., 1996: 1015).