Vantor seeks an Ontology Engineer with TS/SCI clearance to design, implement, and maintain knowledge graphs and semantic data models for modern software and data platforms. You will collaborate with engineers, data scientists, and client teams to model complex domains, define ontologies and taxonomies, and integrate heterogeneous data sources using semantic web standards (RDF, OWL, SPARQL). Responsibilities include developing reusable ontology components, governing metadata, ensuring data quality and lineage, and optimizing query performance. You’ll work in an agile, low-ego environment focused on craftsmanship, automation, and scalable cloud-based solutions for mission-driven clients.