The disclosure describes an axial lead connector assembly for an implantable medical device (IMD). The lead connector assembly facilitates electrical connection between an implantable medical lead and circuitry contained within the housing of an IMD. A connector header defines an axial stack bore to receive an axial stack of in-line connector components. The connector components define a common lead bore to receive a proximal end of an implantable lead. The in-line stack of connector components may include seals, electrical connector elements, a strain relief, and a locking device, each of which defines a passage that forms part of the lead bore.