Molded headers, implantable signal generators having molded headers, and associated systems and methods are disclosed herein. An implantable signal generator in accordance with a particular embodiment includes a can having a shell and a battery positioned at least partially within the shell. An output terminal can be operably coupled to the battery and positioned to provide electrical power to a signal delivery device. A pre-molded header having a plurality of openings can be coupled to the can, and the output terminal can be positioned at least partially within an individual opening.