As 2012 winds down, and as media outlets online and off begin to roll out their traditional end-of-year Top 10 lists, LIFE.com is gamely joining the fray.

Well, we’re sort of joining the fray. After all, 99 percent of the photos we’ve posted this year were taken decades ago. To be exact, they were made by LIFE staff photographers between 1936 (when the magazine launched) and 1972 (when it ceased publishing as a weekly). With the exception of one gallery of photos from the very early 1990s, none of the pictures that appeared on LIFE.com this year were taken after 1972. And while quite a few of the stories we wrote might have referenced or been inspired by current events, it simply feels closer to our mission as a website to look back not at the year that was, but at the decades in the middle part of the 20th century — when LIFE was at its peak — for our very own end-of-the-year “Top 10″ feature.

[Buy the book, 75 Years: The Very Best of LIFE.]

Here, then, is a tribute to 10 of the most iconic LIFE covers. Selecting just 10 from the more than 2,000 covers that graced LIFE through the years might seem like an impossible task. Foolhardy, even. But we trust that no one in his or her right mind would quibble with the Yousuf Karsh cover of Churchill in 1945 (slide 3), for example, or with the inclusion of Leonard McCombe’s “Marlboro Man” image from 1949. Is anyone going to seriously argue that the 1969 classic, “To the Moon and Back,” does not belong in any list of the most iconic LIFE covers — or a list of the most iconic magazine covers, period?

Could Lennart Nilsson’s landmark photo of a human fetus in utero for the April 1965 “Drama of Life Before Birth” issue possibly be left off such a list?

And then there’s the April 1945 cover featuring W. Eugene Smith’s photo from Iwo Jima, as Marines take cover on a hillside amid the burned-out remains of a banyan jungle at the very instant that a Japanese bunker is obliterated. It is a picture, a great picture, that captures the violence and sheer destruction inherent in war perhaps more graphically than any other ever published in LIFE.

[MORE: See the gallery, "World War II: Pictures We Remember."]

The photographers represented here, meanwhile — those on staff (Ralph Morse, Margaret Bourke-White, Larry Burrows) and those who worked on contract (Philippe Halsman, Karsh) — are among the very best who ever picked up a camera. That there are literally scores of others who shot for LIFE who just as aptly fit that description speaks volumes about the magazine itself, and about the quality of photojournalism that was practiced by dedicated men and women in those years when LIFE was still a weekly to be reckoned with.

Not everyone will agree with all the choices in this gallery. And that’s all right. But from our perspective, these covers provide as strong and as varied a sampling as one is ever likely to find of 10 distinct pictures that capture the very best of LIFE through the years.

And that’s a Top 10 we can live with.

— The Editors