"Black Elk" is not a word, but a name of a famous Lakota Sioux medicine man and holy man. However, if we consider the two separate words, "Black" and "Elk," we can easily find numerous antonyms for both.
For "Black," antonyms could be "white," "light," "fair," "blonde," "bright," "colorful," "cheerful," and "optimistic."
For "Elk," antonyms could be "small," "tiny," "little," "diminutive," "weak," "incompetent," and "ineffective."
However, it is important to note that names are unique and special to each individual, and it is not appropriate to assign antonyms to them. Black Elk's name has significant cultural and spiritual meaning.