This thesis uses qualitative design to explore autistic children and young people’s (CYP) experiences with and perceptions of imaginary companions (ICs) and paracosms (imaginary worlds). A consultation period was held before data collection in which autistic researchers supported with the interview design and offered guidance around best practice. Interviews were held with 8 autistic participants aged 7-17: all had multiple ICs and six had paracosms. The data was analysed using Reflexive Thematic Analysis (Braun & Clarke, 2022) and the overarching themes showed the ICs and paracosms support the CYP’s emotional regulation, provide them with a sense of control in their lives, give access to friendships and a sense of belonging, and enable the CYP to make sense of experiences and their identity as individuals growing up with additional needs. The findings are mapped to Maslow’s Hierarchy of Needs (1954) and demonstrate the overall purposes served of improved wellbeing and access to self-actualisation. The findings challenge research which connects autism to an imagination deficit (ie. Ten Eycke & Muller, 2018; Craig and Baron-Cohen, 1999), as well as the Theory of Mind hypothesis (Baron-Cohen, 1995), the Social Motivation theory (Dawson et al., 2005) and the theory of Sustained Imagination (Harris, 2000). Strengths of this research include the methodological design, enabling participants to access a traditional interview, though the study is limited by a small sample size and a heterogenous sample. Future research which explores the phenomena of autistic CYP’s imaginary activities on a wider scale yet remains person-centred and inclusive is advised, alongside using further participatory measures.