It’s already been said, but I’m going with Corbett Monica based on this pic
Note the hairstyle, nose and ear shape.
Thanks.
Your manners are terrible.
But I suppose we all have to be bad at something.
Aw, heck no, it doesn’t. Of all the names that have been offered so far, Dick Cavett is probably the absolute worst candidate–and that’s saying something because some of the names have been absolute turkeys.
Following up on a previous post:
“Your honor, the entire membership of the Straight Dope Message Board witnessed this crime, but not one of them can identify the defendent. Motion to dismiss!”
Jonathan Harris. That looks very close!
How about Ricardo Montalban?
And a profile, showing the shape of his nose and chin…
Better merge, other one was off by a pixel.
Does anyone know if a show Titled “The Name of the Game” was nominated for a Photoplay Award (or any other award that may have assembled these entertainers [is that still under discussion?- I’ve seen Emmy mentioned in this thread, and I believe Oscar])?
If Name of the Game was not nominated that year, it is obvious that Sid Ceasar was trying to clone Jonathan Harris and cross contaminated himself into the result. If NotG was nominated, then it was Bob Stack who was cloning Jonathan Harris and got too involved in his project.
The mystery guest is likely to be a producer or director and basically unknown to the public, but Robert Stack isn’t any worse than some of the other suggestions in this thread.
Also, I didn’t get the lost wallet in the wall reference mentioned previously, I believe by SiamSam.
A still unsolved mystery. That is, we know whom it belonged to, but the person just seems to have disappeared.
It almost looks like a thinner-faced George Lazenby, but not quite. Dunno who it is. Are we sure this is an authentic contemporary group photo, and not a PhotoShopped pic with Some Anonymous Guy inserted just to drive us bonkers?
Thank you Snake-Hips. It seems NO work is to be done today thanks to The Straightdope.
Yes. I continue to believe this is a hoax, for these reasons:
***As you mention, at least some of the people involved would have had publicists active on their behalf. Information about the purported group appearance on the Tonight Show, as well as any event that the Tonight Show appearance was supposed to promote or commemorate, would have appeared in many newspapers of record. Given the interest that many people take in show business (as well as the fact that the contents of newspapers-of-record have been digitized), these stories and notes should be available online.
***On those lines: Four sources have been given for television-schedule listings that purportedly show this Tonight Show episode having taken place as the photo would imply: the Post-Standard (of Syracuse), the Independent Press-Telegram (then of Los Angeles); the Bridgeport Post; and the Daily Kennebec Journal. (All are linked in post number 114.) These are all small, relatively obscure, and in some cases no-longer-in-business publications.
It’s far easier to spoof or hack a “TV listing” in such sources than it would be to do so for, say, The Los Angeles Times, Chicago Tribune, Hartford Courant, Boston Globe, Tampa Bay (formerly St. Petersburg) Times, etc. In other words, it’s suspicious that the only “evidence” that this Tonight Show was a real broadcast comes from hackable/spoofable webpages.
***It’s an odd coincidence that of the (literally) thousands of episodes of Johnny Carson’s Tonight Show that are listed and described in both wikipedia and IMDb, the night claimed to be that on which the photo was taken is blank on both sites.
***A perusal of those same listings reveals that it was very unusual for this many guests to appear on the show. Given that it was so unusual, it’s odd that descriptions of this event can’t be found on the Internet (even though it clearly happened pre-Internet, descriptions and photos commemorating many such events from the period have been uploaded.
These were Important People of their time. It’s unlikely that they would appear on Carson’s show en mass simply to promote some other event (unless the event were for a major charity).
***The seating arrangements are a bit odd. It’s hard to believe that Marlo and Danny Thomas would have been sitting apart like that, for example.
The photograph is skillfully made. As ThelmaLou pointed out in post 112, there is a strange suggestion of cowboy boots on the tuxedo-clad Mystery Man (among other things), but on the whole it passes inspection pretty well. It would be interesting what someone with a sophisticated graphics program would find in it, though.
The hoax, too, is skillfully made. If the hoaxer had presented the photo and said “look at this great group of people who appeared on Carson’s show!” then we’d have been focused on the claim that this group of people really did appear together on some episode of Carson’s show…and we might have dismissed it much more quickly. But the Mystery Man angle was a better choice–in looking for matches with the MM, we have tended to simply accept the ‘they all appeared on Carson’s show’ premise as a given.
I find myself hoping that this is part of someone’s doctoral dissertation. (!) Certainly it brings up valid questions about the difficulties of identifying people from photographs (with obvious law-enforcement implications).
(My original post on this theory: http://boards.straightdope.com/sdmb/showthread.php?p=17337476#post17337476
Pretty sure it’s not Cavett. For one thing Cavett is fairly diminutive at 5’6" and MM appears 5’10’ or more, plus the hair is wrong as Cavett seems to have had the beginnings of a comb over at the time.
Plus, like Earl Snake-hips Tucker said, Cavett doesn’t look anything like him. 
Browse photos of Cavett in Google Image Search and you’ll see he really looks nothing like MM.
I spent a lot of time looking at pictures of Robert Stack and had the same reaction you did. It’s not a bad match, but the Mystery Man seems a bit thicker in the lower-face than Stack did at the time of The Name of the Game.
One note about the hair: a LOT of show-biz men wore full wigs (think Shatner), so we can’t conclude a great deal from the hairline. Stack generally appeared with brown curly hair, but some of his hairpieces have higher hairlines than others.
Just for the record, Robert Stack was a serious answer . . .
I was too young to remember “The Untouchables”, but when I first opened the photo I wondered how long it would be before someone would say: “That’s Rex Cramer, from Airplane!” Photoshop two pair of dark glasses on the mystery man and you will see I am right.
Now I have to go catch up on this guy’s lost wallet.
Based on this picture of Sid Cesar as an older man, I think it is him. Same curve of the nose, laugh lines around his mouth, same chin shape, same ear lobe. Yep, I think it is Sid Cesar.
As far as the “boot” goes, if you look at the magnified image it becomes clear that you can see MM’s shoe, with the upper part of the so-called boot likely being MM’s shin showing through a light thin dress sock.