Hemingway?

The Wizard of Oz!!!!!
j/k

Not Hemingway or Wizard of Oz ..

I organized flower shows, beauty contests, dog shows, and poultry
contests, but the most popular were baby contests such as the fattest
baby or the handsomest twins.

If you heard my first and middle initials, you would probably
know immediately who I am...

P. T. Barnum?

Yes!

off to you, Animated Puppets...

Wow... that was a stab in the dark only based upon the initials clue.

I got somebody, but let me formulate the clues...

1.) My father was the local Chief of Police.

2.) I saved a drowning man's life in 2004 while on vacation in Hawaii by swimming out and bringing him back to shore.

3) For many years, I wrote a monthly column for the bodybuilding magazines Muscle & Fitness and Flex.

David Hasselhoff

Not the Knight Rider.

4.) During my army service, I won the Junior Mr. Europe contest (I went AWOL during basic training so I could take part in the competition and then spent a week in military prison).

Arnold Schwarzenegger

Yep.

5.) Besides being the Chief of Police my father was also a member of the Nazi Party.
6.) My accent was so bad that my voice was dubbed in early films, or I played a mute.
7.) I'm well known by my catch phrases.

Yay! O.k. I've got someone in mind. Give me a few minutes, here.

------------

1.Father was a local pharmacist who worked night shift.
2. Lived with maternal grandmother for several years, but...
3. Was sent away to St. John's Military Academy in L.A. at age 10.

That's really more than 3 clues if you're reading between the lines... and I think you are. Oh well. I'm new here.

Laurie:

I'm really happy to see you here in this thread. We appreciate new blood.

I have no idea who this is. As a guess: William Calley, Jr.

'Fraid not. Thank you for your kind greeting.

I'll give another clue or two . Let's see...

4.After military academy, attended San Diego High school and lived with father.

Colin Powell

No.

5.Father advocated for a career as a doctor, so enrolled at University of California, Berkeley as a pre-med student.

6.By senior year, though, found real interest was in writing in acting and was drawn to communal, familial aspects of the theatre.

Keanu Reeves

Gregory Peck? ...

Gregory Peck is correct.