"Lonely Water" (1973) is a British PSA about water safety, featuring Donald Pleasence as the voice of the Grim Reaper. I love its old-school, horror movie vibe.
The Grim Reaper in this PSA stands around in its hooded cloak, near potentially dangerous bodies of water where children are playing.
He makes a remark about a "Danger, No Swimming" sign: "Only a fool would ignore this, but there's one born every minute."
This amusing yet convincing PSA from the Central Office of Information ends after the Grim Reaper says "I'll be back (Pre-terminator)," in an eerie voice.