What's your favorite TV show, documentary or movie about a serial killer?

[Blow by blow, the passion dies]

The Devil's Double.

[Rand]

I have probably seen The Silence of the Lambs 30 times.

[Meclazine for Israel]

Snowtown.

Worth researching what happened before watching the movie.

True story. Hard to interpret the gravity of the reality these people endured until you know happened beforehand.

[Benjamin Frank 2.0]

Fictionalized movie: The Todd Killings (1971)  The real full story is even more bizarre, but the very disturbing nature of the whole situation seems to be accurately portrayed.  
Based on the true story of Charles Schmid who was called 'The Pied Piper of Tucson.'

The film changes the time of the murders to the then current time and shifts the setting from Tucson to a San Diego suburb. The biggest change though involves largely dropping Charles Schmid's mafia connections. There is a scene where this is hinted at where the Schmidt character (named in the film 'Skipper' Todd) has a disturbing conversation with a person who is clearly suggested as being in the Mafia (played by Ed Asner), but the rest is left out.

For those who want the spoiler:
The disturbing nature of the film/real story is that all the young teens who hung around with Charles Schmid/Skipper Todd knew he was a serial killer but at best none of them cared (some of the teens assisted him in burying the bodies.) This is why he had the nickname 'The Pied Piper of Tucson.'

As is accurately shown in the film, he is only caught because his girlfriend finds him cheating on her and turns him in.

At the end of the film, as Schmidt/Todd is being taken away by the police, one of the young teens says "What are we going to do now without Skipper?"

[The world will shine with light in our nightmare]

American Psycho, of course. Great book, too.

[Fmr. Pres. Duke]

Silence of the Lambs will always be the correct answer.

[Crumpets]

Neither a TV show, nor a movie, nor a documentary, but the Atlanta Monster podcast by Payne Lindsey.

[I spent the winter writing songs about getting better]

Mindhunter on Netflix.

[Progressive Pessimist]

'The Greasy Strangler.'

[President Johnson]

Mr. Brooks.

Kevin Costner playing a successfull Oregon businessman whose secret vice is being a brilliant serial killer. I've always been fascinated by vicious fictional characters of extremely high intelligence with a charming side to hide their dark instincts when it suits them.

[Sol]

You're Wrong About, especially their episodes on the D.C. Sniper Case. Mildred Muhammad is a major FF.

Not very interested in "True Crime" stuff, which often feels like it glamorizes or exploits this kind of thing.

[Landslide Lyndon]

Silence of the Lambs will always be the correct answer.

[Mr. Smith]

Psycho.

Great book too.

[VBM]

Death Note

[HAnnA MArin County]

Monster with Charlize Theron as Aileen Wuornos has always been my favorite.
Dahmer with Evan Peters from American Horror Story is a good one, too.
Zodiac with Jake Gyllenhaal and Mark Ruffalo gets an honorable mention.

[T'Chenka]

Titane (2021 film from France)

[emailking]

American Psycho, of course. Great book, too.

I love the opening monologue.

[MyLifeIsYours]

Henry: Portrait of a Serial Killer

[CosmoKramer]

The Hannibal show easily. Way better than the other crap out there.

[Lumine]

Citizen X, about Chikatilo. For a TV movie, absolutely brilliant - if chilling - stuff.