Martinican poet, novelist and cultural theorist Édouard Glissant (1928–2011) rejected contemporary simplistic notions of creole hybridity popularised in the 1980s and 1990s in favour of a unique and explicitly antiessentialist construct of Caribbeanness—a form of being that embraces place while shunning any associated ideas of rootednesss. Throughout his work, there is a constant tension between the local and the global, the particular and the universal, the essentialist and the homogenising, a tension that is never resolved but used creatively to stake out an emergent third position against a backdrop of a metaphorical Caribbean seascape. The purpose of this article is to shed light on a central idea developed by Glissant: the importance of acknowledging opacity in the encounter with the Other, in contrast to idealised notions of transparency as inherently desirable. This ‘right to opacity’ has been embraced in poststructural theory, postcolonial activism and contemporary art. However, I argue that opacity is also a highly relevant notion in clinical contexts, as an essential resource for understanding concepts such as first-person, second-person and third-person perspectives in the phenomenology of mental health and illness. For illustration, I point to a number of clinical tools and approaches—such as the Cultural Formulation Interview, Therapeutic Assessment and the employment of a not-knowing stance in mentalisation-based treatment—that successfully incorporate a respect for opacity as a core value in the clinician-patient encounter. This article is not an attempt to offer a definitive how-to guide on how to make use of the ideas of Édouard Glissant in the clinic; instead, I hope to inspire further discussion about how various notions of opacity and transparency come into play for mental health practitioners and how acknowledging alterity and difference may contribute to more fruitful and respectful ways of engaging with the patient-as-Other.