The oldest i remember was a G1 Ultra Magnus. The car used to transform into a small white Prime and the trailer into a big Ultra Magnus. I loved that toy, wish i still had it.

I had a Zorro puppet (does it need to have legs to be an action figure ?)

Then I had tons of Marx army men - Americans (green), Germans (gray), Japanese (tan) and Russians (dark blue).

The other was the Geronimo 12 inch Indian figure by Marx.

Some of the 1st ones that I can recall having:

Mego:
Spider-Man
Batman
Robin
Hulk
Joker
Penguin

Pocket Heroes:
Batman
Superman
Robin
Wonder Woman
Spider-Man
Hulk
Green Goblin
Captain America
Lex Luthor

Dukes of Hazzard 3 3/4 in:
Boss Hogg
Daisy
Bo
Luke

Universal Monsters 3 3/4 in:
Frankenstein
Dracula
The Mummy
Phantom of the Opera
The Wolf-Man
The Creature from the Black Lagoon

Star Wars:
Luke
Han
Chewie
Imperial Gaurd
Lando (2 Versions)
C3PO
R2D2


Other 3 3/4 in:
Lone Ranger
Tonto
Flash Gordon
BJ from M.A.S.H.

And later... Masters of the Universe

The first figure I can recall getting is opening a boxed Mego Robin. Must be one of the reasons why he is still one of my favorite characters!

John

1st action figure: 12" Boba Fett or Shogun Warrior Mazinga Z.

1st action jet: G.I. Joe X-14 Skystriker

1st action HQ: G.I. Joe Headquarter

1st action spaceship: Millennium Falcon

1st action castle: Castle Greyskull

What I was most into growing up in the 70s and 80s was Masters of the Universe and G.I. Joe.

Yes, I was spoiled. Now I have to pay bills and find time and money to play with and pay for my toys.