Steve Biko is in a sense a major spiritual leader and inspiration for me. He was the founder of Black Consciousness movement in South Africa; his ideas apply to many oppressed peoples, and have laid the foundations for liberation of mind and body for many, many people. Words I can construct cannot do him justice. For more information, the following books are useful:
"I write what I like" by Biko; "Biko" by Donald Woods (a very important white reporter friend of Biko's, he got "banned" for reporting on the true nature of Biko's brutal murder);
For those who do not like to read, you can see the movie "Cry Freedom," which is pretty good, but is told from Donald Wood's standpoint instead of Biko's (a directors call... a bit unfortunate), but good never the less.
Also check these websites:
A short Steve Biko biography
ANC statement on the 18th anniversary of Biko's murder