If Clemens was that good, you’d be able to spell his name.
Ferret legging - Reg Mellor
I know very little about the sport beyond the glimpses (and several matches) I’ve seen on Eurosport and whatever channel they show that kind of stuff on in the UK, and if you asked me to name a snooker player, Ronnie O’Sullivan would be the first to come to mind, followed by Davis, followed by Hendry, and then I’m drawing a blank. Of course, this is biased by the time I was out there ('96, then '98-'03).
How about darts? Phil Taylor?
I was looking to see if figure skating was mentioned. For me, it’s Fleming or Katarina Witt.
Gymanstics: Nadia Comaneci (mentioned previously)
Swimming: I go with Mark Spitz, but I’m sure that’s also a function of age (I’m 40). I actually had to jog my brain for a second or two to remember Phelps, but I followed the Olympics very closely in the 80s and, while that was well after Spitz’s time, he was just so legendary, I always associate swimming with him immediately.
My IQ is lower than his ERA 
The real test is, if a bunch of NON-sports fans were surveyed by “Family Feud” and asked “Name a famous athlete from the sport of ____,” whom would they name?
Even a housewife in France who never watches boxing knows probably knows who Muhammad Ali was. Even an Australian who’s never watched baseball probably has a vague idea who Babe Ruth was. Even Americans who’ve never paid attention to soccer kind of know who Pele and David Beckham are.
So, when you nominate people, ask yourself “Would a tepid sports fan on another continent know this person’s name or recognize his face?”
Exactly.
And nobody can ever convince me that the top answer (among people who didn’t follow cycling) wouldn’t be “Lance Armstrong”.
It’s like above, someone is saying there are better known pitchers than Nolan Ryan. They then list 20 people better than him, in their opinion. I haven’t heard of anyone on the list save for one or two.
If you’re going to ask everyone (this includes people who haven’t seen the sport but just knows of the names or have heard of them), most people are just going to say “Nolan Ryan”… (or Babe Ruth, Yogi Berra, Sandy Koufax, Mickey Mantle, Joe Dimaggio). They’re not going to know anyone else, but say, the names that have been repeated over and over for the last FORTY-FIFTY years.
No offense to you, Madsircool. I’m just saying… Warren Spahn? Bob Gibson? Who the hell are they? 
I’ve never heard of them.
And while obviously it’s not a “Oh, well, if YOU’VE never heard of them, then they can’t be considered one of the best players of the sport, right?” case, it is one of those instances where me (a non-baseball watcher) am giving the answers as a non-baseball watcher would. Most non-baseball watchers are going to say “Who is Warren Spahn? Never heard of 'em. Ah, but NOLAN RYAN I’ve heard of”.
So it’s not a “who is better?” topic… I mean this thread with the intent of a “who would be the MOST WIDELY KNOWN?” thread; who is the person who would be on the MOST PEOPLES’ LIPS when they answer? …Which, IMO, is the REAL “signature” player of each sport.
Without even looking up any stats, he was clearly not the equal of just these pitchers who pitched since I was born in 1971; Steve Carlton, Pedro Martinez, Tom Seaver, Roger Clemens, Greg Maddux, Bob Gibson, Phil Niekro or Randy Johnson, and I may be missing someone. He’s probably not quite as great as Gaylord Perry. Prior to my birth he is clearly eclipsed by Walter Johnson, Cy Young, Pete Alexander, Lefty Grove, Christy Mathewson, or Warren Spahn, and if we start naming pitchers who maybe didn’t have as long a career but achieved higher levels of greatness certainly we must name Koufax, Hubbell, and a few others. I’m sure I have missed several names.
But I’d still pick Nolan Ryan as baseball’s SIGNATURE pitcher. He’s the most famous pitcher.
From an American point of view, sure. The US paid no attention to Road cycling (and little to track cycling) up until the 1980s. (There were a few one-offs, but LeMond started the serious interest). And certainly Armstrong is a bigger name than Lemond now.
But road cycling has been huge sport in Europe for over a century. There have been many great names - Coppi, Anquetil, Hinault - Merckx is the legend, however.
In Australia, for a very long time, we used ‘Oppy’ - Hubert Opperman - as our Signature Cyclist. We’ve had plenty of good ones since the 70s - but none have really captured the imagination or become the standard. But no one talks about Oppy anymore (because of the new guys) - so I guess ours is - ooooh, probably Cadel Evans (having an identifiable christian name or distinctive surname helps to be a signature performer).
Nolan Ryan has the same problem Bob Gibson has, a generational one. Outside of the baseball universe, I doubt that the general public knows either.
Amongst film fans who are not baseball fans I would think that Jim Bouton is the most widely known. Not only was he a famous author but he had a TV show and was also featured in Robert Altmans The Long Goodbye.
By sheer coincidence, today one of my co-workers was dealing with a wild-eyed and muscular client who was getting loudly confrontational.
“Like the Macho Man Randy Savage,” he explained.
By the way, if we include Pro-wrestling as a sport, then the answer is obviously Hulk Hogan. 
Or Andre the Giant
Speaking as a non-baseball fan, I thought Babe Ruth was the most famous pitcher. Didn’t he pitch? He’s definitely more famous than Nolan Ryan.
Wha?
As far as baseball players, I would have trouble putting Jim Bouton in my top thousand candidates for signature player. I’m somewhat aware of both 1970’s TV and baseball, yet I had no idea Bouton had a TV show. I see there was a show based on his book Ball Four, but it was cancelled after 5 episodes.
You could have just as easily have written “Amongst swinging couples who are not baseball fans I would think that Daryl Strawberry is the most widely known.”
High jump: Dick Fosbury, he of the flop.
Ah, but there you go; “didn’t he pitch?” You had to ask.
Yes, he pitched. But that’s not what he is most famous for. He’s famous for hitting home runs and making the Yankees the sport’s signature franchise. Nolan Ryan hit, too, but he’s not famous for it.
Walter Payton is one of the NFL’s most memorable and beloved players and is at least the signature Chicago Bear. In is career he completed a number of passes to receivers. Would you say he’s a signature quarterback?
Walter Payton was never listed as a quarterback and never started a game as a quarterback. Ruth was listed as a pitcher and started games as a pitcher (in fact, IIRC he was a pitcher before he became a great hitter). So that’s a terrible analogy. Ruth may not be famous as a pitcher, but he was a pitcher. John Madden is much better known as an announcer and video game “consultant” than as a coach, but he’s still a very famous coach.
For purposes of recognition, it helps a lot if the athlete in question has some kind of shtick or catch phrase, or if he’s made his presence known in pop culture.
Muhammad Ali had that. Joe Louis, who was just as iconic in his day, didn’t.
There have been many tennis players at least as good as John McEnroe. But no one remembers Ivan Lendl or Pete Sampras as anything but quiet guys who won a lot of matches. By contrast, even now, if I was playing tennis and got jobbed on a close call, I could jokingly yell, “YOU CANNOT BE SERIOUS!!!” And I think most people would get that I was doing Johnny Mac.
For women’s tennis, I think Billie Jean King’s famed match with Bobby Riggs made her an icon of the game in a way that even better players (like Steffi Graf and Martina Navratilova) never could be.
Jack Nicklaus was a much better golfer than Arnold Palmer, but I think “Arnie’s Army” was a phenomenon that made Palmer more popular and more famous than Jack. (Tiger, I suppose, eventually trumped them both.)
For gymnastics, Nadia Comaneci and Olga Korbut belong at the top, because they were the ones who inspired girls all over the world to start taking gymnastics lessons. Before 1972, women’s gymnastics was not prime time TV programming in the US. It was afterward, thanks to Olga Korbut (who wasn’t even the champion that year!).
Fidel Castro is probably more famous than Ruth. Is he baseball’s signature pitcher?