On Monday, some 2 million rowdy revelers — many likely dressed as slutty kittens, nurses and cowgirls — will line up for hours along Sixth Avenue to watch the 43rd annual Village Halloween Parade.

But Lee, the man who started it all, is boycotting.

“It just isn’t the same,” the puppeteer, 81, told The Post at his home and studio in the West Village, where, from 1974 to 1985, he created the 40-foot skeletons and papier-mâché creatures that were the stars of the event.

“It’s no longer good for kids. They have to stand behind a barricade, they can’t see anything, they can’t move. I think that’s why there aren’t as many [kids] anymore.”

The first Village Halloween Parade, 42 years ago, was a small community affair, with maybe 200 adults and children making their way from Jane Street by the Hudson River to Washington Square Park. Lee — whose three kids ranged in age from 3 to 9 at the time — turned the route into a work of performance art, with fantastical ghouls perched on stilts and witches doing song-and-dance numbers in doorways and on fire escapes along the way.

“It took the Village kind of by surprise,” Lee recalled. “Some people would look out their window and then come down and join us, but a lot were just staring in awe.”

The second year, the number of participants spiked to 500. And in 1976, Lee made the event — then done in conjunction with Theater for the New City — its own not-for-profit entity.

But the parade’s growing popularity meant that Lee had to make unhappy compromises. In 1978, the city required him to put up police barriers for crowd control, and that hindered the freewheeling-community vibe.

“Until then, people could flirt with each other and have interchanges, and all kinds of surprise things would happen,” Lee said. Like the time the parade absorbed a group of gay men who were on their way to a party dressed as Imelda Marcos’ shoes. “That was hilarious.”

He took part in the event for 12 years, but grew disenchanted when, in 1985, officials had him shift the route to Sixth Avenue. That meant the parade could no longer start at the Westbeth Artists Housing complex, where Lee and his family lived (and where Lee’s son, by then a teen, would rappel down the side of the building in a bug costume).

“What had started out as a community event had become a city event,” Lee said. “The spectators were standing six or seven deep — it just seemed like they had become total onlookers” rather than actually taking part.

Since leaving the parade, Lee has gone once or twice, but he generally avoids the whole shebang.

He admitted he occasionally feels a “pang” when he remembers the early days of the parade, but is happy doing his own thing.

Now, to celebrate Halloween, Lee packs up his spookiest puppets and heads to the Cathedral of Saint John the Divine in Morningside Heights for an artsy, sit-down evening of silent horror films and organ accompaniment. (This year’s event took place on Friday.)

“That’s my new Halloween Parade,” he said.