I don't think anyone has posted any vintage tennis autographs on here, perhaps an indication of the lack of collecting interest.
I've picked up a few signed tennis books along the way, and have found Bill Tilden's signature particularly appealing, given both its appearance, his success as tennis's first superstar in the US and his difficulties with his post-tennis career.
I just picked this up from his book The Pinch Quitters (the book itself I believe is very hard to find)