First Appearance: Black Panther v1 #7 (January 1978)
Appearances: Black Panther v1 #7, Black Panther v2 #29, Fantastic Four Unlimited #1.
Years Active: ? to the present.
It was established (admittedly, in what seems to have been an unpublished Conan story) that the lineage of the Black Panther stretches back far beyond T'Challa and even the Golden Age Black Panther, Azzari the Wise (the grandfather of T'Challa). A Black Panther was shown riding with Conan, although I do not know whether it was in a Hyperborean Wakanda or some other land. But if the Black Panther cult was active in 10,000 B.C.E., then presumably it has been active since then.
In the original Black Panther series the history of Wakanda was laid out in some detail; after the vibranium meteor fell, a number of Wakandans mutated into "demon spirits" and began attacking their "friends and neighbors." T'Challa's ancestor, Bashenga (that's him on the left), became the first Black Panther--no date is given for this event beyond it having happened many centuries ago--and closed the vibranium mound to outsiders, forming a cult that guarded it and fought to keep the "demon spirits" from "spreading across the Earth."
Bashenga wore the attire of a (stereo)typical African native, but with a black panther cowl which covers the top of his head, rather than his face, ala Hercules and the hide of the Nemean Lion.
Note: In v1 #7 T'Challa noted that his family had "never been known to die in bed," which to my eyes implies that there's a lineage of Black Panthers that have always been active.
Note: The preceding story was contradicted by Fantastic Four Unlimited #1, which portrayed "Chanda," T'Challa's grandfather (his other grandfather, perhaps?), as founding the Black Panther role during World War Two. The story also implies that the Wakandans originally came to Wakanda because of the vibranium mound. I don't really see how these two stories can be reconciled without a lot of heavy lifting, so I'm going with the original story, which I find preferable in every way. However, Bob Harras has definitively stated that Wakanda did not get involved in the events of World War Two, so the story in Fantastic Four Unlimited #1 is invalid.
Later Note: Black Panther v2 #29 showed T'Chaka, the father of T'Challa, encountering Captain America (I) in Wakanda. So...the revised (as of March 2001) continuity for the Black Panther has T'Chaka as the WW2 Black Panther, invalidating the FFU #1 story but re-establishing a Black Panther as being active during WW2 and showing Wakanda at least aware of the events of WW2, if not getting fully involved.