PORTLAND — Whatever you do, keep your eye on that familiar-looking banjo picker. And don’t let his mild-mannered, professorial demeanor or those Clark Kent glasses fool you. The guy invented cool while you were still a bewildered high-school sophomore, desperately attempting to remember your locker combination.

One glance at the banjo player’s epic-length bio and you’ll instantly understand why they call Steve Martin the human cannon ball.

While he may not be a member of Mensa or a Mormon (the Internet rumor mill has mistakenly claimed him for both teams), he does hold the title as the most hyphenated overachiever in all of show business: actor-author-producer-playwright-bluegrass demigod.

While the rest of us clip coupons or forget to floss, Martin has starred in dozens of cinematic crowd pleasers (from “The Jerk” to “It’s Complicated”), written plays (“Picasso at the Lapin Agile”), published children’s books and hosted the Oscars on several occasions.

If all that weren’t enough, he has also romanced the likes of Meryl Streep, Goldie Hawn and Diane Keaton on screen.

Though there’s an entirely different love affair going on these days.

“I just love the sound of the banjo,” the 66 year-old Martin says. “For some people, it may be the mandolin or the fiddle or the guitar, but for me, it’s the banjo. I really can’t explain it. It’s primordial. Whenever I would listen to a band playing, I could literally part — with my ears — the other instruments and just focus exclusively on the banjo. I really love both its melancholy aspect and its dynamic speed.”

Martin’s banjo, in all its manic-depressive glory, will be featured when he performs with the Steep Canyon Rangers at Merrill Auditorium on May 18. The show will almost certainly sell out — and with good reason. Martin’s banjo playing isn’t part of some cockamamie reinvention gimmick. It’s the real deal. And he isn’t about to join that select group of celebrities (we’ll call them Don Johnson, David Hasselhoff and Bruce Willis) who seemed to believe that their Nielsen ratings guaranteed them entry into the Rock ‘n’ Roll Hall of Fame.

“Sometimes when actors try to become musicians, there’s a great resistance,” Martin says. “And I’ll tell you why that is. It’s not that they’re trying to become musicians. They’re trying to become rock stars. And that’s always kind of ludicrous. It’s like they’re not paying their dues. … Bluegrass is natural for me because I’ve loved it ever since I first heard it around age 17. But you know, I don’t call myself a natural musician. I had to learn how to be a musician. And comedy I had to learn, too, but I did have an instinct for it.”

Much of Martin’s Portland Ovations appearance will be devoted to performing selections from his entertaining new album “Rare Bird Alert” (Rounder Records), which promises “the highest class bluegrass in the world.” And on that score Martin certainly delivers. The 13 songs he wrote for the album run the gamut from the defiant “Jubilation Day,” which celebrates the end of a stormy relationship (“let’s always remember the good times … like when you were out of town”) to the plaintive ballad “You.” Besides guest vocalists Paul McCartney and the Dixie Chicks, the album is also graced with some of the wittiest lyrics this side of Cole Porter.

In “Atheists Don’t Have No Songs,” Martin pays tribute to the nonbelievers among us and proves that even godless existentialism can be a hot riot: “Catholics dress up for Mass and listen to Gregorian chants. … But atheists just take a pass, watch football in their underpants.” Martin says that this particular song has been a consistent favorite with audiences regardless of their spiritual affiliation. “What I actually say in the show is that religious people have all of this great art and music, and atheists really don’t have anything. So, I thought it would be really funny to write a hymn just for atheists.”

Tony Trischka, who produced “Rare Bird Alert,” is widely considered one of the foremost banjo players in the world and is someone Martin obviously admires. Trischka will serve as Martin’s opening act at Merrill, though this isn’t the first time the two showstoppers have appeared together.

“We shared a bill in New York City in 1974, before Steve hit it big,” Trischka recalls. “He was doing stand-up at this club in the Village. And I heard him play then and he sounded really good. And after hearing him through the years, I knew that he was a really talented banjo player. It’s a big part of who he is. But what really impressed me is that Steve is able to deliver all of these tunes that are fresh and new and exciting. … He’s an intellectual with very wide-ranging tastes, so his lyrics are going to contain all of that. …Whatever he does is unique.”

After his Portland performance, Martin’s tour will take him to concert halls all over the map, from Knoxville, Tenn., to London. While he insists that he isn’t out to spread the “bluegrass gospel,” he hopes that he’s doing his part to introduce more people to the kind of music that he’s always been passionate about.

“I’ve never taken a poll, but I think a lot of the audience that comes to see our show either doesn’t know bluegrass or maybe just kind of knows bluegrass a little,” says Martin. “And I think the audience always leaves thinking, ‘Wow, that was fantastic. …’ Not so much thanks to me, but thanks to the Steep Canyon Rangers, who are terrific. … I’m also doing comedy in this show, so it’s never just one song after another. That could get old if you’re not into this form of music. So, we do a complete show. And my feeling is that people leave really happy and, hopefully, they’ll want to continue sampling this kind of music.”

By fall, Martin will be back on the big screen in the eagerly anticipated comedy “The Big Year,” which also stars Owen Wilson and Jack Black.

After all of these creative accomplishments, what does the ultimate multitasker do for an encore? “I think continuing in this vein is what I’d like to do,” Martin says. “I’ve thought about possibly writing a musical, but I’ve already written a couple of plays for stage. And so, in terms of the broad strokes, I’ve done what I’ve wanted to do and I think I’ll just keep doing the things I’m doing.”

Mark Griffin is the author of “A Hundred or More Hidden Things: The Life and Films of Vincente Minnelli.” He may be reached at mgriffin1368@gmail.com.

Go and do

WHAT: “An Evening of Music and Comedy with Steve Martin and the Steep Canyon Rangers”

WHEN: 7:30 p.m. Wednesday, May 18

WHERE: Merrill Auditorium, Portland

TICKETS: $45 to $65. Call PortTix at 842-0800 or visit www.portlandovations.org.

At their May 18 concert at Merrill Auditorium in Portland, Steve Martin and the Steep Canyon Rangers will perform selections from the new “Rare Bird Alert” album for which Martin wrote 13 songs.