DC Comics | DC EDITION: "All-New Collectors' Edition: Superman vs. Muhammad Ali." | 1978  
Cover art & pencils: Neal Adams. 
Inks: Dick Giordano & Terry Austin
Signed:  Muhammad Ali

This treasury edition is truly a historic piece: it features the iconic characters of Superman and Muhammad Ali and is signed and dated by Muhammad Ali himself. There are other signed copies of this book, but I've never seen a dated copy. The signature date -- May 28th,1978 -- places it shortly after the comic's publication, and at a specific time late in Ali's boxing career. Because the book suffered numerous delays -- going from an original publication date of fall 1977 to spring 1978 -- Ali was no longer World Heavyweight Champion by the time he signed this copy, having been dethroned by Leon Spinks in February 15 1978 in a bout that was named Ring Magazine's upset of the year.  He would later regain the title in his rematch victory on September 15th, 1978, which was also his last professional win.

If you're a comic book fan OR a fight fan, this piece should be in your collection.