MM (idea)

Marilyn Monroe.

Mickey Mouse.

Mad Max.

Manfred Mann.

Margaret Mead.

Mr. Mister.

Mary Magdalene.

Michael McDonald.

Mrs. Miniver.

Mad Magazine.

Melissa McCarthy.

Mandy Moore.

Milo Minderbender.

Michael Maltese.

Michael Myers.

Marshall Mathers III.

Moose Malloy.

The Marlboro Man.

Mike Mignola.

Michael Moorcock.

Mandrake the Magician.

Moses Malone.

Martian Manhunter.

Marty McFly.

Ming the Merciless.

Malcolm McDowell. 

Meghan Markle.

Marlee Matlin.

Megan Mullally.

Matthew Modine.

Mickey Mantle.

Martin Mull.

Marilyn Manson.

Marcello Mastroianni.

Margaret Mitchell.

Miss Marple.

Michael McKean.

Method Man.

Miss Moneypenney.

Mister Miracle.

Michael Mann.

Mary Marvel.

Mitch Miller.

Matthew McConaughey.

Minnie Mouse.

Michael Moore.

The Metal Men.

Erm. And an abbreviation for millimeter. And how you write "2000" in Roman numerals. And how you write "million" in financial documents. Gaaah, usefulness is too hard.

Thanks to generic-man and others for assistance.