With literally hundreds to choose from, creating a list of 20 of our favorite duets was a mountainous task. But there ain't no mountain high enough to keep us from doing it. This list is by no means comprehensive, just a mix of tracks - both well-known hits and off-the-beaten-path gems - that we've loved. (And for all you Michael McDonald fans, "Yah Mo B There" just missed the cut.) For an even longer list and to share your own favorites, check out boston.com/ae/music/blog. -SARAH RODMAN
AIN'T NO MOUNTAIN HIGH ENOUGH
YOUR PRECIOUS LOVE
Marvin Gaye & Tammi Terrell. This Motown duo is synonymous with duets, so, naturally, we had to squeeze in two, including the classic uptempo jam and the elegant finger-snapper written by another famous duo: Ashford & Simpson.
WHERE IS THE LOVE
Donny Hathaway & Roberta Flack. This golden-throated pairing killed us softly with its tale of frustrated love on the down low and set the standard for '70s R&B pairings.
Lionel Richie & Diana Ross. The Brooke Shields movie may have faded from memory but not this tender ode to first love.
ISLANDS IN THE STREAM
Kenny Rogers & Dolly Parton. The twin titans of country crossover, and Kenny Rogers, look for love with a fine-tooth comb, uh-huh.
THEY CAN'T TAKE THAT AWAY FROM ME
Louis Armstrong & Ella Fitzgerald. You can't take anything away from this spitfire jazz classic.
LEATHER & LACE
Don Henley & Stevie Nicks. The one-time first couple of '70s rock join in raspy-voiced bliss to compare closets.
BABY, COME TO ME
James Ingram & Patti Austin. Is that a quiet storm looming in the distance? Best to take cover in each other's arms.
THE BOY IS MINE
Brandy & Monica. Oh, no she didn't! Oh, yes she did.
DON'T GO BREAKING MY HEART
Elton John & Kiki Dee. So much fun they covered it on "One Day at a Time."
NO MORE TEARS (ENOUGH IS ENOUGH)
Donna Summer & Barbra Streisand. Sisters do it for themselves and kick that trifling man out together.
Johnny Cash & June Carter Cash. The Man in Black and his spicy bride at their most playful.
George Michael & Mary J. Blige. Wham, a hip and fresh read on a Stevie Wonder treasure.
KINGDOM OF RAIN
Sinead O'Connor and The The. We're still feeling the chills of the lyrics from this one: "Our bed is empty/ the fire is out."
James Taylor & Carly Simon. A funky '70s update of the Charlie and Inez Foxx '60s hit.
Gram Parsons & Emmylou Harris. Love may hurt, but these two make it sound so good.
Iggy Pop & Kate Pierson. The Stooge and the B-52 make a surprisingly pretty pair on this touching tale of yearning.
George Jones & Tammy Wynette. Classic country heartbreak from a classic country couple.
STATE OF SHOCK
Mick Jagger & the Jacksons. Seriously odd but totally funky, and how can you beat Jacko and Jagger trading lines like "you got me deep-fried"?
Nick Cave & PJ Harvey. Dark, sexy, and a little scary. We'd expect nothing less from these two tackling a murder ballad.
Barry Gibb & Barbra Streisand. OK, this is the most aptly titled entry on the list. It oughta be illegal.