Embodiments disclosed herein include pre-terminated fiber optic connector sub-assemblies, and related fiber optic connectors, cables, and methods. In certain embodiments, an optical fiber stub is pre-installed in a ferrule bore of a ferrule of a fiber optic connector sub-assembly, to provide the pre-terminated fiber optic connector sub-assembly. The optical fiber stub can be pre-installed in the ferrule bore prior to termination of the fiber optic connector sub-assembly. Because the pre-terminated optical fiber stub disposed in the ferrule bore is not directly accessible through a ferrule body of the ferrule when a field optical fiber is disposed in the ferrule bore for fusion splicing, the ferrule has properties that allow thermal energy to be directed through the ferrule body into the ferrule bore. In this manner, the optical fiber stub pre-installed in the ferrule bore can be fusion spliced with the field optical fiber to terminate a fiber optic cable.