The UK had a lot of fantastic examples of these. For example, Donald Pleasance voicing “I am the spirit of still and silent water.”
I lived in an area with a lot of abandoned quarries that made for great diving places as long as you didn't care that you might be diving onto a rusted upturned supermarket trolley. Only a couple of kids actually died, but as an adult I can understand why our headteacher gave us a speech about the dangers of them before every summer holiday.
George Lucas allowed his characters to be used in several PSAs. As a young Star Wars nerd during that era, I loved getting to see these when they aired.
William Talman (Hamilton Burger on Perry Mason) was the first celebrity to come out against smoking. He filmed a PSA that was, like Yul Brynner’s, released post mortem.
A couple of hard hitting 30-ish second PSAs from Australia regarding railroad grade crossing safety. Graphic yet restrained. The second one gives me chills.
Back in 1963 or '64, Vic Morrow and Rick Jason did a PSA for (I’m pretty sure) US Savings Bonds in their Combat! uniforms with tanks and jeeps in the background. Watching this at age 8 or 9, I was in seventh heaven! :o
Here’s my favorite one: a PSA from 1973 for equal pay featuring Batman, Robin, and Batgirl. Batman producer Bill Dozier provides the opening narration. Burt Ward and Yvonne Craig reprise their roles as the Boy Wonder and Batgirl. Adam West wanted to distance himself from the Batman character, so they hired Dick Gautier to fill in as the Caped Crusader.
They’re quarries full of things like broken shopping trolleys, reeds, underwater currents and other dangers - being able to swim helps, but it’s still dangerous. I never understood the attraction because they’re also freezing cold.
There was a PSA (by the Franciscan Brothers IIRC) ca. 1970.
It showed two white men in suits, one around thirty, the other older, rushing through an airport.
In their haste, they crashed into a child carrying a box with game pieces, scattering them.
The young man was stunned when the older man knelt down and helped pick up the pieces. He smiled awkwardly at the child, clearly conflicted as his younger, hot-headed colleague admonished him:
"My God, come on, we’ll miss the plane!"
As the old man got to his feet, the child asked him, "Are you God?"
This atheist still wishes I could find this online.