Long John Addams was the great-great-great-great-great-grandfather of Gomez Addams.
He was a pirate who secured the family fortune, and wrote about his exploits in The Tale of Long John Addams by Long John Addams, as told to Long John Addams, copyright 1699, all rights reserved. There is a picture of Long John in the house. He was married to Lady Penelope Addams. Long John's brother was Curly Addams.
The New Addams Family episode:
Long John was portrayed by Glenn Taranto.