Granted, Michelle Phillips was 65 years old in that second photo, so to compare her with her 23 year old self was stretching it.
Let me offer instead, Michelle Phillips in her 40s.
Donald Sutherland. I thought he was goofy looking, now he’s distinguished
Madonna. I was never crazy about her appearance when she first became famous, but she hit her peak at right about 40 in the “Ray of Light” era (late 1990s).
I just thought of a good one. Don’t want to jump through hoops right now to link to pics because I’m on my phone, but . . . Mary Louise Parker.
Weird Al Yankovic.
Julia Louis Dreyfus.
Look at the early season of Seinfeld, and compare those to that later seasons and how she looks now. A lot of it was the God-awful outfits and bad hair, but still.
I think most of these will be. Women who were in their twenties and thirties during the 1980s and early 1990s would have a hard time looking worse now than they did then.
I’ve been watching American Idol lately, and I don’t remember Jennifer Lopez (41)ever looking this good before.
Leonard Cohen–he was a weird looking young man, but he’s much better now
Sigourney Weaver–tremendous
Tom Cruise–never liked the babyface thing he had going as a younger man.
Phillip Michael Hall–he was so scrawny and nerdy, but he has only gotten better as he ages
Susan Sarandan–sexy sexy sexy, time has been kind to her
Sharon Osbourne–not gorgeous, but infinitely better than she used to be.
Some of this (HRC is a great example, Tina Fey is another) is going from someone who dresses themselves without much awareness, to someone who has been coached and styled by professionals. Not that they aren’t good looking people, but they’d have been good looking younger with money and advice that they didn’t yet have access to.
That was a bad photo of HRC with her, as Dangerosa pointed out, styled unfortunately. Young Hillary was quite pretty in my opinion.
When I saw the pictures of a high-school age Sarah Palin in her first book, I was impressed that she wasn’t especially attractive. Not bad-looking or anything, just not as hot as I was expecting, based on how good she looks now.
The way she plays off her looks today (and the spoiled-brat vibe she gives off when she doesn’t get what she wants) made me think she’d always been like that.
Obviously, by the time she entered beauty pageants, things had changed. But there must have been a time when she wasn’t just getting by on her looks.
It’s one of the few things that’s ever improved my opinion of her. 
Brian Eno (now aged 62)
The emaciated Bowiesque look just didn’t work for him back then
Who needs hair anyway?
Gillian Anderson has gone from cute-in-a-nerdy-way to smokin’-fuckin’-hot. I think growing her hair out has much to do with it.
Bonnie Raitt, Emmylou Harris, and Joan Baez.
Second Julia Louis-Dreyfus. She was kind of doughy plain when she was in her 20s on SNL, but when she hit 30 on through her 40s, she got really cute.
maybe it’s cuz I always had a thing for her but I nominate Judy Davis