Notes:

I'm not sure where to put this image. There isn't an entry on dragons or evolution.
Me either, posting it on MLP for now, if anyone has suggestions, do comment

1940s: Unnamed Dragon (The Reluctant Dragon)
1950s: Maleficent (Sleeping Beauty; the movie came out in early 1959, but it still counts.)
1960s: King Ghidorah (Ghidorah, the Three-Headed Monster; because Godzilla technically isn't a dragon.)
1970s: Elliott (Pete's Dragon)
1980s: Falkor (The Neverending Story)
1990s: [Left] Dragonite (Pokemon; because Charizard wasn't a dragon yet), [Right] Mushu (Mulan)
2000s: [Left] Cassie (Dragon Tales), [Right] Jake Long (American Dragon: Jake Long)
2010s: [Left] Toothless (How to Train Your Dragon), [Middle] Smaug (The Hobbit), [Right] Spike (My Little Pony: Friendship is Magic; yes, I am aware that he's an MLP character.)