Taking Sartre’s existential theories as a point of departure, this thesis examines the theme of self-destruction as a phase resulting from the loss of identity among Igbo characters, both during and after British colonisation. Mainly concerned with colonialism and its aftermath, this thesis focuses on selected novels by the Nigerian writer, Chinua Achebe, especially Things Fall Apart and Arrow of God, set during the British colonial era, and No Longer at Ease and A Man of the People, set in a post-colonial context. I contend that this theme of self-destruction can not only be examined from colonial/post-colonial perspectives, but also from an existential angle by focusing on the absolute freedom of choice or free will of self-aware characters, who can make and take responsibility for their own decisions, and whose ‘authentic existence’ plays a major role in their decision-making. Consequently, the most important questions explored in this thesis include the following: To what extent can the self-proclaimed superiority of white colonisers over the ‘inferiority’ of colonised blacks lead to the latter’s self-destruction? Moreover, what is the impact of self-awareness on the decisions made by colonised people, which eventually result in their self-destruction? Likewise, how does the representation of self-destruction vary from one character to another? And finally, how can the investigation of self-destruction help colonised people to decolonise their own country and resist the effects of colonisation?