Here is a page about the original of "Uncle Tom" - Reverend Josiah Henson, with a photograph.

"Recognized for his contributions to the abolition movement and for his work in the Underground Railroad, he rose to international fame after Harriet Beecher Stowe acknowledged his memoirs as a source for her 1852 anti-slavery novel, Uncle Tom's Cabin. It was Henson's life experiences that inspired Ms. Stowe's creation of the character Uncle Tom in her 1852 outcry against slavery.

In fact Uncle Tom in the book is in no way "an Uncle Tom" in the way that term has come to be used. Stage and early screen adaptations probably led to that distortion.

Here is the book itself online.