Is the African American artist Theadius McCall still alive?

Not sure if this is a definite answer to your question, however note
the past tense his daughter uses when referring to him:

"December 21, 2003 is the day my mother, Wauneta Lonewolf, passed of
lung cancer. She worked strenuously on bridging cultural awareness,
Native American philosophies and education to races of all kinds. She
was full blood Ogalala Lakota and my father, Theadius McCall, was
African American..."

http://www.finalcall.com/artman/publish/article_2191.shtml

I hope that helps.

Best regards,
Rainbow

On the other hand, the SOCIAL SECURITY DEATH INDEX does not list him
among the deceased, which of course suggests that he is still living.
In addition, PUBLIC RECORD FINDER shows a Theadius W. McCall, age 51,
in Nevada. I can't verify that this is the same fellow but I've yet to
find anyone else with an unusual first name like that.

Please let me know if this works for you as a convincing answer in the
absence of hard evidence.

SOCIAL SECURITY DEATH INDEX
http://ssdi.genealogy.rootsweb.com/

PUBLIC RECORD FINDER
http://www.publicrecordfinder.com/

tutuzdad-ga

I believe the artist would be older than 51 if still alive:

"Theadius had a small gallery in San Antonio, Texas in the early 60's.
He was doing a series of dramatic portraits in blacks and blues about
a character named "Faye Harlot". One was "Faye's Self", another was
"Faye's Uncle", the loan shark. He grew up in NYC and painted there.
He also did a group portrait of the astronauts who flew including Gus
Grissom, which was run on the front page of the San Antonio newspaper.
I purchased a couple of his paintings..."

http://dart.fine-art.com/aqd-asp-im_98193-buy-m.htm

Rainbow~