WALL-E (I think it’s G?)

Star Trek the Motion Picture pretty gnarly transporter death with screaming, very slow 'think piece' pace and subject matter

2001 A Space Odyssey Mind bending, bizarre, slow. Mature subject matter and homicidal computers

Willy Wonka and the Chocolate Factory (1971) Acid trip of a movie with some bizarre things that have to have killed some kids

The Land Before Time

I know it's old, but the first thing that came to my mind was Bambi. Maybe not the most mature subject, but watch that with a kid and then field the "where's his mom?" question.

The Secret of NIMH, maybe

Watership Down

2001: A Space Odyssey.

Old Yeller

20000 Leagues Under The Sea

2001: A Space Odyssey

The Ten Commandments

Battle of Britain

The Andromeda Strain

Jerry Seinfeld Apologizes for Interspecies ‘Sexual Undertones’ in ‘Bee Movie’

my bad that was PG

Silent Running. Bruce Dern scifi where he murders his shipmates to preserve a forest.

Andromeda Strain. Those townfolk turned to dust was pretty horrifying.

Dark Star- The Captain is a frozen corpse they talk to and everyone dies.

The Andromeda Strain is rated G and it shows tits, dead kids, and threatens to nuke a government facility

Maybe The Last Unicorn.

Funny story.

Any movie made before the MPAA system was implemented was grandfathered in as "G"

There were some wild pre-Code movies that are legally G.

For shows, I'd say probably Batman: TAS. It deals with some heavy themes like drug abuse and trauma, and imo doesn't really dumb anything down that much.

Quest for Camelot had some gnarly monsters

Straight story

The Strait Story.

It is David Lynch’s only G rated movie and it is excellent.

Stalker. Rated G in some counties, PG in others.

The Fox and the Hound, most of the movie is relatively typical Disney fare, but the ending had its "PG" moments.

All Dogs go to Heaven, this production felt different compared to other animated movies when I watched it as a kid.

Taken.