Why wasn't the poltergeist Peeves in the Harry Potter movies?

They filmed some scenes with Peeves in the first film, but he was cut before the film was released. The character wasn’t revived for the later films.

I found a few interviews that touch on the topic of Peeves.

First, there was an interview with BBC Norfolk with Chris Rankin, who played Percy Weasley, where he explains that they actually shot scenes with Peeves, but they were cut from the film:

What's the longest time you've ever spent shooting a scene?

The longest scene I've ever shot was on this first film. It was the scene with Peeves the Poltergeist. We shot it in Gloucester Cathedral cloisters.

Sadly it never made it to the final take although I hear Chris Columbus is going to be making a director's cut in which it will be reinstated.

This would have been Philosopher’s Stone, and he was played by Rik Mayall. I’m not aware of that director’s cut being released, or any of that footage being widely available.

So why were those scenes cut? There’s an interview with Chris Columbus, who directed the first two films, which makes it sound as if it was just

Apart from casting, what was the biggest challenge putting the film together? Was it the sheer scope of the thing?

[…] I loved the book so much that it was extremely difficult to cut elements out. One of my favourite characters never made the film – Peeves, the annoying, sort of, mischievous poltergeist. Those sorts of things, there was just too much to film. Our first cut of the film was about 3 hours and 20 minutes.

As other posters have said, Peeves didn’t play a particularly prominent role in the books: although he gets a few lines, he’s not critical to any plot points. If they were trying to shed material, you can see why Peeves would be one of the characters who gets cut.

Alternatively, there’s also an interview with Steve Kloves, who wrote all but one of the films, who offers his take on why Peeves was dropped in the final cut:

On a different note, what about some characters in the books who never appeared on screen? What ever happened to Peeves?

Peeves was always an issue. Chris Columbus was determined to put him in the first movie. I think there were even some technological problems with him initially, and [not] being satisfied with how he looked. He was always a bit tangential. I think [Argus] Filch, in a way, became that energy in the movies. And he was actually sort of beloved at a certain point, Filch. So I think to have Peeves, it would have felt like we were doubling up on that. It's not exactly the same but it's a bit like that. But he was a character we all loved.

As mentioned by DForck42, Peeves is not a central character in Harry Potter movies. On top of that, in the story Peeves is shown to be doing a lot of destruction (think flying objects, utensils). The film makers would not have wanted to spend precious dollars on doing SFX for a character who has no effect on the story and is very hard to recreate faithfully on the screen.

From what I recall Peeves had almost no influence on the main story arc of the series, so he was rather easy to cut out of the story. Also I believe he shows up less frequently as the series continues, so he's not missed as much in the later parts.

Nearly Headless Nick (NHN), although not tied very close to the story, is tied in a few key parts of Harry's character development, so he was kept in.

In the novels, the world of the ghosts is detailed, with complicated relationships that affect the storyline in later books. Moaning Myrtle, the Bloody Baron and the Grey Lady all play important roles later in the novels where extra characterization would have made the films stronger (in my opinion). Peeves himself is a worthwhile sideline to the "getting rid of Umbridge" storyline, but only if his trickster attitude and kinship to Fred and George has already been established in earlier books and movies.

"Cackling madly, [Peeves] soared through the school, upending tables, bursting out of blackboards, and toppling statues and vases. Twice he shut Mrs. Norris inside suits of armour, from which she was rescued, yowling loudly, by the furious caretaker. He smashed lanterns and snuffed out candles, juggled burning torches over the heads of screaming students, caused neatly stacked piles of parchment to topple into fires or out of windows, flooded the second floor when he pulled off all the taps in the bathrooms, dropped a bag of tarantulas in the middle of the Great Hall during breakfast and, whenever he fancied a break, spent hours at a time floating along after Umbridge and blowing loud raspberries every time she spoke."

A description of Peeves' behavior after Fred and George's departure

However, when the first movie began filming, many of the long-term implications of the ghost characters definitely weren't published. It's questionable if J.K. Rowling had fully planned out their importance, especially enough to convince the filmmakers to fully develop the characters. It makes sense to cut Peeves if he is only ever a source of commotion and a minor plot catalyst, which is the role he played in the first two books.

Based on the same set of information, fully fleshing out Nearly-Headless Nick makes sense though. He welcomes Harry to Gryffindor, establishes just how magical the world is, and is a major part of the second book's storyline. Not only does he have some emotional moments with Harry, but he is essential to the development of the plot. He gets Harry to the Death Day party, which is visually interesting to film in a book that doesn't have as much action early on as others in the series. His petrification helps Hermione identify the monster and is an important emotional beat, being the most easily recognized of the victims before Hermione, and he has several other major events. As that book was published in 1998, three years before the film release of Harry Potter and the Sorcerer's Stone, the filmmakers would have known that his character needed to be developed for the storyline to proceed smoothly. Peeves is never so essential, particularly in the first several books.

Peeves was in the philosophers (sorcerers stone) however he was not needed for the rest of the movies so the character wasn't included

Peeves is only there to make you laugh, but Nearly Headless Nick is included for improving Harry and fights in the final battle. That's why he is included

Peeves was also more important to the final book because it was alluded to that he was a part of the magical protections of the school just like the suits of armor were. It was demonstrated in the fifth book when he was given tacit approval to rain hell on Umbridge, then in the final battle when he's told to defend the castle, as he's a near unstoppable distraction to intruders and gives you a large advantage in a fight if he's on your side.

Also, please check out this explanation from actor Rik Mayall, who states that he actually played the part of Peeves in the first movie, but was left out. Sounds convincing, I think.

He wasn't needed. His character isn't essential. Frankly, I think that he is very essential to Fred and George's plans in the end of the fifth book when they leave Hogwarts in an array of fireworks. But other than that, the only reason he is needed is to cause destruction even though he is in the first book a lot.