Series that drastically changed

Hey everyone! I was wondering if anyone could recommend me some long standing comic series that drastically changed their concepts or focus throughout their runs.

For example, Stormwatch started out as a big guns/big pouches super book. In the second series it evolved into what would soon become the Authority. In the third series the focus shifted to a human team that dealt with superpowered disasters and had more of a political overtone. The fourth series was similar, but added more of a street-level vibe.

The first run of X-Force is another good example. it shifted from Liefeld's big gun wet dream to a group of mutant celebrities in the span of it's 129 issue run.

So in short, I'm looking to get into some comic series that evolved over time with changes of characters, themes, styles, whichever.

Thanks in advance!

100 Bullets. It shifted from its premise into something grand. And unlike the series that you mentioned, it was written by one writer, though I don't know if you can call the chance that drastic.
BB

Sandman was originally meant to be a horror comic. It turned into an overall fantasy / mythological tale.

Action Comics went through some pretty major changes due to how long it lasted.

Thunderbolts. It was the story of criminals posing as heroes. Now it's just the story of poser heroes.