Do you have any particular look or style in mind?
This pack from
Copplestone's Ngoni range has three quite nice candidates:
(They come with a couple of Zulu-type shields)
Also
North Star Africa has some options in their Congo range:
They also do some leader types in their Matabele range, including a fellow on a horse.
And
Foundry do a pack of leaders in the original Darkest Africa range:
(Probably some options on their Casting Room Miniatures offshoot's website, I think they still sell that Zulu War range from a few years ago.)
Empress also have some options in their Zulu War range:
Off the top of my head that's about it for starters, but there are probably some others I'm forgetting.