I posted the search for "The Rule of Threes" because I was looking to see if there was any reference to the game Jean and I play. We note whenever a well-regarded celebrity dies, and watch the news to see which two other celebrities follow them into the great beyond. Since people are dying all the time, you can stretch this to fit in any situation. But the variation is to try to name broad categories of expertise, i.e. an actor, a politician, a writer.
This month's trio starts with a musician/comedian and an actor: