OSU Football great Archie Griffin, when I won a Reading is Fundamental poster competition and he visited my elementary school.
Historian David McCullough, who graduated from my Pittsburgh-area prep school long before I did (I mentioned the school both times I’ve met him at book signings, several years apart, and he just lit up both times).
Civil War historian Ed Bearss, several times. He’s 93 now and slowing down a bit.
U.S. Secret Service Agent Paul Landis, who was in Dallas that fateful day: Meeting one of JFK's Secret Service agents - Miscellaneous and Personal Stuff I Must Share - Straight Dope Message Board
Warren Commission staff lawyer Burt Griffin, who focused on Jack Ruby in the investigation.
Bill Clinton twice, both before and after he was President. I most noticed the bags under his eyes.
Mike Dukakis (I joined his campaign staff early on, when he was still personally interviewing everyone), Dick Gephardt (redder hair than I expected), Al Gore (very blocky shoulders), Jesse Jackson (a very tall guy) and Paul Simon (we complimented each other on our bow ties) during the 1988 campaign.
2001: A Space Odyssey actor Keir Dullea: I met Keir Dullea tonight! - Cafe Society - Straight Dope Message Board
The Grand Budapest Hotel (and many other films) actor Willem Dafoe: In which I meet Willem Dafoe - Cafe Society - Straight Dope Message Board
Nobel Peace Prize winner Archbishop Desmond Tutu, who was my college’s commencement speaker.
Ohio governors Dick Celeste and Ted Strickland, and attorney general Lee Fisher.
U.S. representatives from Ohio Marcy Kaptur, Doug Applegate, Stephanie Tubbs Jones and Marcia Fudge, and U.S. senator Sherrod Brown.
Howard Dean when he was Lt. Gov. of Vermont and still a practicing physician.
John Kerry during the 2004 campaign.
U.S. Supreme Court justices Antonin Scalia (he had dinner with several students at my law school including me, and was charming), Stephen Breyer and Ruth Bader Ginsburg (at a meet-and-greet for lawyers newly admitted to the court).
And a highlight for me, President Obama and the First Lady: In which I meet the President and smooch the First Lady - Miscellaneous and Personal Stuff I Must Share - Straight Dope Message Board