Bill Cosby was an artist who “changed the world,” “America’s Dad,” an icon of stand-up comedy, a breakthrough TV performer with Emmys and Grammys and national recognition in every field he moved into.

He was a tireless education activist in front of the camera, and a behind-the-scenes activist who not just broke barriers, he opened doors for others — forcing the integration of the film and TV stunt-performer industry.

And “He was a rapist who had a really big TV show once.”

Comic-turned-filmmaker W. Kamau Bell’s “We Need to Talk About Cosby” is a cultural history lesson, a work of biography, and in the tradition of “Surviving R. Kelly” and “Allen v. Farrow,” an expose of a famous person whose private persona can only be described as monstrous. For decades, the most famous Black entertainer in America drugged and raped women — scores upon scores of them.

Bell’s four-part Showtime series unfolds as biography, marking the Philadelphian’s early years, his showbiz breakthrough as an emulator of comic pioneer Dick Gregory who found the way to success and riches in America was to become “Raceless Bill,” with “family friendly” stand-up. His don’t-talk-about-race credo saw him rewarded with multiple TV series that were landmarks of their time.

But all the way through this Showtime series, in every episode as Cosby launches his career, first tastes fame, and then reinvents himself again and again, there were victims and pieces of evidence that kept coming out, a sexual predator “telling us who he was” on stage, on TV shows and in interviews. The signs were there, Bell shows us and Cosby-watchers and others tell us, suggestions of criminal activity and the attitudes that led to it, the “rape culture” that only #MeToo put into the public eye.

His story became the most precipitous fall in American public life.

Bell interviews victims, co-workers, academics, entertainment historians, psychotherapists, lawyers, journalists, the researcher/curator of “Hamilton’s Pharmacopia,” an expert on “drug facilitated sexual assault,” and shell-shocked fans.

The series firmly places Cosby at the pinnacle in the history of American comedy, and as a Black role model whose omni-present face and voice made him an icon of generations. And Bell asks the hardest question, one that comes up whenever Roman Polanski, Michael Jackson, Picasso or Woody Allen’s names are mentioned.

“Can you separate the art from the artist, and should you?”

“Talk About Cosby” is rich in detail and thorough in the breadth of interviews Bell conducted. The generous sampling of TV and film appearances includes not just samples of Cosby the performer, but cringe-worthy interviews with Larry King, clips of Charlie Rose and Matt Lauer “reporting” on a story that should have made them blush.

There’s a tsunami of facts, achievements often lost with the passage of time — a CBS TV special Cosby hosted, “Black History: Lost, Stolen or Strayed,” that presents what’s been criticized as “uncomfortable” “critical race theory” way back in 1968.

Every episode is filled with achievements and the acclaim and respect that every bad thing Cosby ever did took away from him. And every episode has little clues, hints that maybe “Doctor” Cosby’s Ed.D. wasn’t earned, other signs — his infamous stage routines about “date rape drugs” like Spanish Fly — that maybe the public and African America in general shouldn’t have kept him on that pedestal for so long. The series makes it clear how easy Cosby made it for us to assume his midlife “America’s Dad” guise was just a reflection of his real life.

The first hint that he might not be what he’s seemed was his evolving into Black America’s public scold. That made his “hypocrisy” an easier target when the whispers turned into court cases.

Bell hands interview subjects a notebook PC that to play back incriminating stage routines, interview revelations and even a damning episode of “The Cosby Show” in which he leers about his special “people, they get all huggy-buggy” after sampling his special barbecue sauce. Bell questions interviewees about what “Dr. Heathcliff Huxtable’s” Cosby-selected profession was on “The Cosby Show” — an OB-GYN. His office?

“It was in the basement of their townhouse…Ohhhhhh.”

His manner of manipulation, of using his “power,” is explored. He “mentored” some of his victims, especially when he had the most popular TV show in America. Some of Cosby’s enablers are named, the “serial philanderer” label is examined and the phrase “a LOT of people knew” pops up.

And there are endless, repetitious accounts of how this power figure at the top of the entertainment industry would lure powerless women, offer them drugs or sneak those drugs into their drinks, then heartlessly shame the women with “you got so drunk” and “This was between you and me” threats the morning after.

The series’ thoroughness and the repetition of the predator’s modus operandi can make the outrage feel earnest but somehow muted, with Bell speaking for many in how deflating and disheartening learning all this has been. Despite the many interviews with victims, there are fewer big emotional punches in this series than you’d expect, given the life-altering nature of the crimes.

“Talk About Cosby” is missing an interview with the pivotal figure who brought Cosby down — the outspoken stand-up comic Hannibal Buress — who may want to move on from that October 2014 club appearance, but whose absence is felt. That’s where some of the outrage that the series is missing might have come from.

But by generously sampling Cosby’s greatest hits, by praising Cosby’s philanthropy, Bell masterfully builds us up in between damning indictments. He reminds us of the “monument to Black excellence” that was “The Cosby Show,” its cast and even its set, and of Cosby’s place at the center of American culture. Remembering how high the man rose, how trusted he and his “brand” became makes his fall more disheartening, the reluctance to believe his accusers and the whispers easier to understand.

Rating: TV-MA, graphic discussion of rape, profanity

Cast: Bill Cosby, Gloria Hendry, Lili Bernard, Victoria Valentino, Michael Jai White, Jemele Hill, Michael Dennis, Jelani Cobb, Gloria Hendry, Gloria Allred, Doug E. Doug, Linda Kirkpatrick, Lise-Lotte Lublin, Michael Coard, Rolando Martin, W. Kamau Bell

Credits Written, directed and narrated by W. Kamau Bell. A Showtime release premiering Feb. 6.

Running time: Four episodes @:58 minutes each.