What is charisma, really?
What is it about one personality or persona that draws our attention? That rivets us? And, perhaps even more to the point — especially in light of the picture above — is charisma a quality or a trait that one either has or doesn't have, or is it something that one radiates by virtue of attaining a certain level of notoriety or fame? Would we bother looking at a picture of someone shaving in a men's room in 1965, his head wrapped in a towel, if it wasn't a picture of Frank Sinatra shaving in a men's room in 1965, his head wrapped in a towel?
LIFE photographer John Dominis spent weeks with Sinatra in 1965 — the year the singer turned 50 — emerging with one of the most revealing photographic records of any major performer's private world ever captured on film. From rehearsals in smoke-filled recording studios to Vegas nightclub performances to golf in the Nevada sun to playing with his dog Ringo in his home office to late-night hijinks with his drinking buddies, the Sinatra in Dominis's remarkable photos is at-once far more approachable than the near-mythic bad boy of legend, and more Olympian in the way he dominates every scene. In large gatherings and small, in hotel suites and in sports arenas, virtually every frame Dominis shot makes it clear that, when Sinatra was around, no one else mattered.
Call it what you like — charisma, magnetism, star quality — there's little question that by the time 1965 rolled around, Sinatra had "it," and "it" made his every move, every gesture, no matter how commonplace or trivial, somehow significant. Or, if not significant, at least suggestive of something more. Power, perhaps.
Ultimately, though, what makes a simple picture of Frank Sinatra shaving so weirdly engaging — especially when he's obviously unconcerned with looking cool, or tough, or hip — is that such a picture feels so unexpected, so contrary to the way that, for the longest time, celebrities allowed themselves to be portrayed. Today, of course, when so many pop-culture creatures feel compelled to post, share and tweet every sordid or pointless experience ("Had another hangnail today!") and every ill-formed thought in their heads, a picture of a half-naked singer peering in the mirror as he shaves would hardly raise any eyebrows.
Seeing a bona fide musical colossus unselfconsciously scraping away at his stubble, on the other hand, is so unusual that it somehow doesn't even register as mildly intrusive. Instead, Dominis's photograph is notable, all these years later, precisely because Sinatra is so supremely oblivious to our gaze. It's not that we, the viewers, don't matter; it's just that, having done it all and seen it all in his long, prodigious career, the Chairman of the Board has nothing left to prove.
— Ben Cosgrove is the Editor of LIFE.com