I'm a creature of habit, and I'll admit I've been watching pretty much the same TV shows since the day I was born.
So sometimes, it's easy to miss the TV hosts and stars aging before my very eyes.
Getting older is perfectly natural, but it can be striking when you see how these stars have changed between their first appearances and the latest episodes.
1. Howie Mandel
The America's Got Talent judge has a infectiously positive personality, and he's been lightening up our favorite shows since the 1980s.
Fans may be stunned to see the Deal or No Deal judge once had hair. Mandel says he shaves his head to keep his OCD under control, not hide a bald spot.
2. Joe Mantegna
Since taking over Mandy Patinkin's lead role, Mantegna has been the head honcho on Criminal Minds for more than a decade.
But he was much less intense playing comic relief character "Juan One" on Soap.
Turning back the clock even further, a baby-faced Mantegna was a fixture of the band The Apocryphals in the 1960s.
3. Henry Winkler
He's still making us laugh on Arrested Development, but of course Winkler will always be remembered as the Fonz, from Happy Days.
But do you remember his guest role on Mary Tyler Moore?
4. David Letterman
The late night talk show host was known for being edgy when he debuted in 1982. These days, he's interviewing distinguished guests like Barack Obama on his Netflix series.
5. Bob Barker
Almost two decades before The Price Is Right first aired, Barker made a name for himself as the dashing host of Truth or Consequences.
Barker, nearly 50 when Price debuted, dyed his grey hair black for almost a decade, before accepting the natural color.
6. Oprah Winfrey
Way back in 1986, before she became the Queen of Daytime TV, Winfrey was still all smiles.
For a more drastic change, check out Oprah's groovy haircut from her time at WJZ 13 Baltimore in 1978.
7. Rosie O'Donnell
Believe it or not, O'Donnell was an early reality TV star.
She competed as a stand up comic on Star Search, winning several weeks in a row before handing over her title.
8. Christine Baranski
Before she was a star on shows like The Good Fight, Baranski paid her dues like any other actress.
Okay, so she's not exactly "unrecognizable," but we couldn't help sharing this uncanny snap of Baranski as Maryann on Cybill, the show that made her famous.
9. Drew Carey
Is hosting The Price Is Right stressful?
Carey has certainly gone grey since he took over hosting duties from Bob Barker in 2007. But he's also slimmed down, dropping more than 80 pounds in 2010 to stay in shape for his family.
10 & 11. Pat Sajak and Vanna White
Yes, the dynamic duo have a long history together as co-hosts of Wheel of Fortune since 1982.
Before the game show was a TV phenomenon, Pat Sajak admitted that he and Vanna White would stop by a Mexican restaurant for a drink before each taping.
"I had a great time," he said. "I have no idea if the shows were any good, but no one said anything, so I guess I did okay."
And how's this for a crossover episode: two years before she began hosting Wheel, White competed on The Price Is Right, but didn't take home a "doggone thing" as she remembered.
12. Mark Harmon
Before he was catching bad guys on NCIS, Harmon was stealing hearts as Dr. Robert Caldwell on St. Elsewhere.
But in fact, Harmon's resume goes even deeper than you might expect. A baby-faced Harmon played L.A. cop Gus Corbin on Adam-12 way back in 1975.
13. Alex Trebek
To see the Jeopardy host's first TV gig, you would have to travel way, way back to 1963, when he was on a little-seen Canadian quiz show called Music Hop.
Trebek took over hosting duties on the answer-and-question show in 1984, sporting his signature mustache and a perm that was not long for this world.
14. Tom Selleck
The Blue Bloods star has actually aged remarkably well since he hit our TV screens in 1980, playing detective Thomas Magnum on Magnum P.I.
Rockford Files fans will also recognize Selleck as Rockford's partner, Lance White.
15. Ellen DeGeneres
In the years since her historic appearance on The Tonight Show - DeGeneres was the first female comedian to be called over by the host, a sign of great respect - the daytime talk show host has joked about her fashion sense.
While the outfit may be out of style, DeGeneres' material is still hilarious.
16. Barbara Walters
Walters was already a veteran journalist before The View premiered in 1997.
While she hasn't appeared on air for several years now - officially declaring herself "retired" - Walters produced and hosted American Scandals in 2015.
Check out this vintage snap of Walters as an NBC reporter, from 1953.
17. Martha Stewart
The queen of cookbooks' life is an incredible success story.
After working as a model and a stockbroker, Stewart turned her catering business into a cookbook empire, then added magazines and TV shows in the '90s.
Were you surprised by any of these vintage photos?
Here are more celebrity stories you might like:
