Jack Nicholson, one of the great screen actors of all time, turned 75 this week and, in honor of that milestone, I wanted to publicly say:

Thank you, Jack Nicholson.

Thank you for being so perfect and unpredictable and bold as an actor.

Thank you for having taste in choosing scripts that so often led to memorable quality films.

Thanks for being one of the actors whose films defined the 1970s and 1980s. You were part of a coterie I think of as the post-Brando generation, an outstanding set of actors that included Al Pacino, Robert De Niro, Warren Beatty, Gene Hackman and Dustin Hoffman.

What made you stand out was your wild-card quality. It was shared by Pacino, Hoffman and De Niro, all of whom could be quite funny early on, but who ultimately focused on more serious roles. But you, Jack, understood the value of comedy – and how to find serious material that injected comedy as both leavening and relief.

Hoffman, De Niro and Pacino conveyed an unmistakable ethnicity in their onscreen personas. Beatty was eternally WASP-like; Hackman could portray blue-collar grit or white-collar hauteur.

But Nicholson was always different. His performances have an insinuating quality, a slyness, a canniness that practically oozes from his pores, whether he’s plays a slickster like Jake Gittes in “Chinatown” or a fair-minded knuckle-dragger like Bad-Ass Buddusky in “The Last Detail.” With his characters, it was never a question of whether he had an angle; it was which of the several angles was he going to play.

I’d also say thanks for Nicholson’s willingness to work with a wide variety of directors in material that called for him to be unlikable, threatening and just plain bad news. He was closed-off and small-minded in Alexander Payne’s delicious, “About Schmidt,” a cool but bored adventurer in Michelangelo Antonioni’s “The Passenger” and a smoothly manipulative womanizer-control freak who himself is out of control, in Mike Nichols’ “Carnal Knowledge.”

Yes, Nicholson’s characters lost control – memorably so. Whether it was Jack Torrance in Stanley Kubrick’s “The Shining,” chopping his way through a door with an ax, or Frank Costello in Martin Scorsese’s “The Departed,” pounding Leonardo DiCaprio’s broken hand with a construction boot, Nicholson threw himself into each role with the same crazed energy that earned him an Oscar for “One Flew Over the Cuckoo’s Nest.” Think of the immortal chicken-salad exchange in “Five Easy Pieces,” as Nicholson shifts from reasonable to riotous while trying to order dry toast in a truck stop.

There are books to be written about Nicholson’s career and films, but what I admire most is that, once he hit with “Easy Rider” in 1969, his film choices were comparatively impeccable for long stretches. When he made missteps – such as “Blood and Wine” or “Man Trouble,” both relatively unseen in the 1990s – they usually had to do with loyalty to a pal (in this case, Bob Rafelson, who directed both of those films – but also was a longtime collaborator with Nicholson, directing him in “Five Easy Pieces” and “King of Marvin Gardens”).

Or, as was the case with Tim Burton’s vastly overrated “Batman,” his piece of the financial action made the role impossible to turn down. (Indeed, his Joker was the only interesting part of that wildly overpraised 1989 film.)

Nicholson has sort of slid into retirement gracefully. Since the turn of the millennium, he has made “The Departed,” “The Pledge” for Sean Penn and a quartet of comedies, including “Anger Management,” which showed him severely outstripping Adam Sandler when it came to winning big laughs in a formulaic comedy.

IMDB lists Nicholson as a possible participant in the sketchily penciled-in “Warren Beatty Project.” But you get the impression that Nicholson is happily playing golf, hanging out with his children and grandchildren, reading and rejecting scripts.

With luck, he’s still got a couple of killer performances left in him. It would be nice to see him choose to work with filmmakers like the Coen Brothers, Wes Anderson, Quentin Tarantino, Steven Soderbergh and Paul Thomas Anderson before he’s done, just to see what they’d do with him.

But even if he never steps in front of a camera again, Jack Nicholson is already an all-timer, as emblematic of a certain age in Hollywood – and a certain level of quality – as Clark Gable or Humphrey Bogart were to theirs.

So happy 75th birthday, Jack – and thanks again.