Marty Hopkirk

Within the narrative of the original 1969–70 series Marty Hopkirk is a private detective killed in a hit-and-run incident; he appears at his grave the night after his death and informs his former partner Jeff Randall that he has been murdered. Because of an 'ancient curse' invoked in the pilot (quoted as a verse compelling ghosts to return to their graves before sunrise), Marty is prevented from passing on and remains bound to the world of the living, continuing his partnership with Jeff. The 2000 revival expands this cosmology by naming Limbo as a place where he may go and by introducing other ghosts and a mentor figure (Wyvern) who trains him.

In the original series Marty is typically depicted as a white‑suited spirit; he is incorporeal and visually manifest primarily to his living partner Jeff Randall. The sources note occasional exceptions in which other characters perceive him (for example under special circumstances such as intoxication) and the 2000 revival retains selective visibility while adding visual and social detail via Limbo and ghost mentors.

Marty's primary function is communicative and investigative: he observes, reports information about his own death, assists Jeff in solving cases, and intervenes indirectly in the living world. He is incorporeal, normally visible only to Jeff (with episodic exceptions), unable to complete the usual return-to-the-afterlife transition because of the series' cited 'ancient curse', and in the revival he receives mentoring (Wyvern) and interacts with other ghosts in Limbo, implying the development of additional ghostly skills though specifics are not enumerated in the provided sources.