You know: the minister who established liberal religion in New Orleans, and in his day served, like Thomas Starr King, as a bridge figure between the Unitarians and the Universalists. He has no Wikipedia article; a fact I discovered when I read about Judah Truro, himself an interesting figure.
Writing about Universalist Christianity and improving how churches work
There are one or two biographies published (one back then, the other back in the 1950s or so), so that should help.
We could probably come up with a list of folks who should be on Wikipedia.
A good recent treatment of Clapp can be found in “Unitarianism in the Antebellum South: The Other Invisible Institution” by John Allen Macaulay (2001). I reviewed the book very briefly in UU World back in 2002: http://www.uuworld.org/2002/06/focus.html. Here’s Ann Lee Bressler’s review: http://www.questia.com/googleScholar.qst?docId=5010846984
I first joined UU at First UU New Orleans in 1980. Rev Albert D’Orlando, himself a strong civil rights advocate, frequently referred to Clapp in his sermons. Later, I moved to Austin Tx. Circa 1985, in the Harry Ransom Center’s rare book collection, I found Clapp’s own memoir. The library card showed that nobody had checked it out since 1935. I was surprised to learn that Clapp had been a pro-slavery Unitarian.
Rev D’Orlando is himself one who should be Wikipedia’d. He’s the subject of a mini-biography in “Seven Who Fought”, which Bill Moyers co-authored. (I have a copy around … somewhere.)
The Wikipedia article on Theodore Clapp came to be in June 2015. The link/bridge between Unitarian and Universalists is not clear from the article, meaning, you may know something the authors do not….
There’s more at the source for the Wikipedia article: http://uudb.org/articles/theodoreclapp.html