Just as David Letterman had his painfully awkward "Uma, Oprah" routine and Seth Macfarlane his catastrophically misjudged song We Saw Your Boobs, Harris will be recalled mostly as the guy who presented in his pants.
It was certainly an arresting image, the How I Met Your Mother star clad only in socks, shoes and what are referred to in America as "tighty whiteys." It was a reference to a scene from Birdman, and - like any time Johnny Depp sings - you had to admire the courage, if not the execution.
And at least it was memorable, unlike almost anything Harris actually said.
Bafflingly, given the amount of potential material to work with - the Sony hack; the Interview row; the #OscarsSoWhite Twitter campaign - the script saw Harris referring to Reese Witherspoon as someone he could eat "with a spoon."
The actor was one of a team of 12 Oscar writers. Just think - one of them worked on that humdinger. The other 11 approved it.
Even more puzzling, things had started brilliantly. The first line was by far the best - "tonight we honour Hollywood's best and whitest - sorry, brightest" - a reference to the #OscarsSoWhite debate that followed the nominations.
Then there was the opening song, about the wonder of "moving pictures", featuring Harris, Anna Kendrick and Jack Black - and dancing Stormtroopers.
Harris, a Tony Award-winner on Broadway, pulled it off like Steve Martin or Billy Crystal at their best, putting himself into classic movie scenes while pulling off clever rhymes like "Argo / And Fargo / Or when Marty made his car go".
Having nailed it, he turned to the camera and smiled. "That whole thing? Completely improvised."
It was pretty much the last big laugh he achieved. From there on, flat setups began crashing into flubbed punchlines with the alacrity of a drunk sailor inviting the entire pub to have a go if they think they're hard enough.
There was a predictable joke about Harvey Weinstein (there always is); a bit where he started to talk to the seat fillers and then seemed to immediately lose heart; a routine about his Oscar predictions so laboured it was on the verge of setting up its own union.
By halfway through there was terror in Harris' eyes whenever the camera came to him. A part where he asked David Oyelowo to read an insult about the remake of Annie - which had recast the lead with a black actress - was fist-gnawingly uncomfortable.
It's worth noting, however, that it was this undercurrent of racial politics that gave the night its most memorable moments.
Oyelowo was in tears as he listened to the performance of Glory by John Legend and Common from Selma. It was an intense, powerful performance which had the entire audience on their feet as it finished.
When Glory shortly afterwards gained Legend and Common (under their real names of John Stephens and Lonnie Lynn) the best song trophy, they electrified with a passionate joint speech.
"Nina Simone said it was an artist's duty to reflect the times we live. Selma may be 50 years ago, but it is now, because the struggle for justice is right now," they insisted, and the music that normally strikes up to urge the winners off the stage stayed silent.
Indeed it was a night for politics. Best Actress Patricia Arquette called for equality for women; Best Adapted Screenplay winner Graham Moore urged young people confused about their sexuality to "stay weird"; Best Director Alejandro Gonzalez Inarritu spoke about the Mexicans "who came before and built this incredible immigrant nation".
Meanwhile, at the end - in every sense - Harris fluffed a gag about mispronouncing Chiwetel Ejiofor's name.
In the context of what had preceded it, it struck a particularly flat note. The Oscars aren't going to stop being seen as white and elitist if every year the writers insist on mining this seam of "exotic names are weird and hard to say."
That is hardly Harris' fault. Nevertheless, it really did highlight the contrast of the night: That between black politics and white pants.
Neil Patrick Harris' debut turn as Oscars host was one of the most forgettable for years - although one moment will define him forever.