•Globalized approach towards heavy oil emulsions from colloid science to industry.•Prevalence of bitumen emulsions; their shared mechanism and antithetical roles.•Complexity of heavy oil emulsions lies in oversimplification of heavy oil types.•“Intelligent” chemical application as a solution to the heavy oil emulsion paradox. Heavy oil, commonly defined by high density, viscosity, and heavy components distinguishing it from light oil, has a peculiar nature with respect to emulsification. In this article, we delve into the colloid and interface aspects of heavy oil emulsions and their types (heavy oil-in-water emulsion and water in-heavy oil emulsion) along with their industrial applications and occurrences. We observe the paradoxical roles heavy oil emulsions play at different stages of heavy oil production such as upstream, midstream, downstream (and other related areas). First, indigenous surface-active agents in the heavy oil are discussed along with the upstream efforts to generate chemically stable in-situ oil-in-water emulsion in the reservoir to improve displacement efficiency of heavy oil. Functions of naturally formed heavy oil emulsions encountered at the different stages of thermal recovery applications are also presented. This is followed by the review of mid-stream demulsification and emulsification efforts during the oil processing and production periods. The paper is then finalized with the discussion on the final demulsification attempts in the downstream sector defined by the refining process and wastewater management—along with other relevant areas of oil spill and aquifer remediation. With this comprehensive overview of the roles that heavy oil emulsions play in the heavy oil industry, we hope to interconnect the separate, detached views of heavy oil emulsions existing in distinct heavy oil industry sectors and provide a globalized, big-picture view for enhanced understanding of heavy oil emulsions and their applications. The results from this investigation demonstrate that a comparative approach towards heavy oil emulsions is necessary to bolster a more optimal and dynamic manipulation of functions and properties of heavy oil emulsion throughout the industry.