Over his six-year movie career, the actor John Cazale was in five movies, total: "The Godfather," "The Godfather Part II," "The Conversation," "Dog Day Afternoon" and "The Deer Hunter."

Every one was nominated for the Academy Award for Best Picture; both "Godfathers" won.

In fact, between them, these five movies were nominated for 40 Oscars, including 14 acting nods.

Cazale, a noted New York stage actor playing supporting roles in film, never got one. Not. One.

Most folks, including the people behind the wonderful documentary "I Knew It Was You: Rediscovering John Cazale," which airs Tuesday, June 1, on HBO, see this as a glaring oversight and rightly so. Those five performances are some of the most nuanced and most powerful in late 20th century American film. Cazale's turn as Fredo Corleone in the "Godfather Part II" — damaged, fragile, filled with rage and hurt — is master class.

But I submit that these oversights were a huge, inadvertent compliment. They get to the heart of what made Cazale's work so extraordinary — he simply disappeared into these men that he played.

There's a scene in "I Knew ..." where passers-by are asked to identify Cazale by name from a photo from "The Godfather." They kind of know his name is "Free-do" or "Fredo."

One guy insists the actor's name is Fredo.

Perfect.

The eyes have it

Character actor-spotting is a weird subset of film fandom. Some movie geeks love yakking about auteur theory and directors, some love the hardcore academic studies, fascinated by framing and images and subtext. Some love popcorn movies and swag, queuing up for free screenings and collecting T-shirts.

But being a big character actor fan is mostly about recognizing faces. Leading men? Meh. Women who can open a film? Whatever.

Give us a guy or gal who shows up on an old "Miami Vice" one night as the long-lost best friend.

The excellent (now defunct) blog Fametracker called its stellar character actor section "Hey! It's That Guy!" as this is what most people mumble when they see a hardworking character actor show up on-screen. Character actor nerds know who "That Guy" is.

John Cazale had a fantastic, memorable face — enormous forehead, wide mouth, flat black hair with a hairline forever at low tide.

But people love talking about his eyes. In "I Knew ...," Cazale's old pal Richard Dreyfuss talks about Cazale in the first "Godfather," about his visceral reaction to his father, Vito, being shot while buying fruit, juggling the gun, staring at the body, hysterical on the curb: "Until that moment in front of the car, you don't notice his eyes. Then you never see anything but his eyes. u2026 (It's as if Cazale noted) my character's entrance is here. You could look at that one moment and get him."

As Sam Rockwell points out, also in the documentary, "Dog Day Afternoon" director Sidney Lumet cuts a lot to Cazale's character, the strange-looking bank robber Sal , because "he's got the stakes" in his eyes — desperate, unsure, infused with a latent violence you're sure Al Pacino's character, for all his bluster, would never engage in.

Rockwell joins up-market That Guys such as Steve Buscemi and Philip Seymour Hoffman in praising Cazale's work because people like talking about Cazale, about his love of the process and improvisation, about the level of detail in his performances, about his killer instincts.

Indeed, actors who never show up in documentaries, who maintain a strict bubble around their personal lives, show up in "I Knew ..." — even Robert DeNiro discusses their work in "The Deer Hunter."

Pacino, who starred in three movies and several plays with Cazale, says he learned more about acting from the older man than anyone else: "He taught me about asking questions and not having to answer them. That's the beauty, you open the door to things."

Cazale's two most famous scenes are with Pacino, in "Godfather Part II." The first is Michael Corleone's legendary kiss on Fredo's mouth. He reveals his knowledge of Fredo's betrayal and gives the HBO documentary its title.

Later, when Michael grills Fredo on the details of the latter's betrayal, Pacino orbits Cazale like a distant god above a lax priest, his fury shunted aside until nothing but cold judgment remains. Cazale slumps in a lounge chair during his speech. Terrified and frustrated and almost crying, he yells at Michael without being able to even sit up: "It ain't the way I wanted it! I'm not dumb! I'm smart and I want respect!"

"Dog Day Afternoon" director Lumet heaps praise on this moment: "This is an antisocial, probably terrible man. And Cazale broke your heart."

Not only did he break your heart, he made it look easy. And he did it in all five movies he acted in. Cazale found the pain of these fictional people and put it on the surface without fear, without worrying how it made him look as a man.

He made everyone he worked with better. He made Harry Caul's inner tension more real in "The Conversation." He made Nick and Mike more rugged in "The Deer Hunter." He improvised(!) his famous punch line "Wyoming" in "Dog Day Afternoon" (just see it) and peeled open new layers to the character with one word. He went out to Vegas to learn the casino business and let it make him corny and strange in "The Godfather." And he made Michael Corleone, the brother he sold out and betrayed and nearly got killed, look like the heartless, savage one.

A short career

The documentary's biggest "get" is the famously private Meryl Streep, who dated Cazale for some years and saw him through his early death from cancer at age 42.

"(John told me) 'Oh man, I have met the greatest actress in the history of the world,' " Pacino says in the documentary. Pacino thought Cazale was simply in love with his co-star in a stage version of "Measure for Measure." But "it was Meryl Streep, so he was right," Pacino says.

"It was the specificity of him," Streep says. This is a wonderful comment. Character actors walk an odd line. They are often cast to type, but they want to be able to adapt to any role. They need to be thought of when a certain thing is needed, but they want to show some range. Cazale navigated this brilliantly.

Of course, we have no idea what the rest of his work would have been like. Even the best (or most memorable) character actors fade or never break type. Joseph Cotten's early résumé as a brilliant supporting player is unreal: "Citizen Kane," "The Magnificent Ambersons," "Shadow of a Doubt," The Third Man." But he ended up in lousy movies, the guy who used to be Joseph Cotten turned into a That Guy. As fun as he and his craggy face are to watch, Danny Trejo is always going to pretty much play a thug. Jackie Earle Haley, the kid who all but embodied '70s teenhood on-screen, vanished for decades (welcome back, dude — congrats on "Human Target" getting picked up).

But those guys got the time to make their mark, to become "That Guys." We will never get to see Cazale's unplayed parts, but we're also spared seeing him fade.

I would prefer the parts, as acting is an art that rewards repetition and experience. A high school theater teacher of mine once talked about the rewards of redefining a role night after night on-stage. You can't do that with film. But we talk about these five brilliant performances over and over because each contains a complete human being — Cazale's perfectly imperfect in every one.

'I Knew It Was You: Rediscovering John Cazale'

7 p.m. Tuesday, June 1

HBO