Celebrity careers are like heartbeats. Some move at a consistent rhythm, with strong steady beats. Some feel occasional palpitations: moments of blockbuster success. Then there are those random murmurs, beats that are neither strong nor weak, movies that are neither good nor bad, but show that a body — or career — still has a pulse.

But, sadly, every career seems to have its moment of flat-lining. Only a lucky few can be revived by the great defibrillators that swoop in and breathe life back into a dying career.

John Travolta is legendary for his near-career-death experiences. One of the sexiest men alive in the late 1970s, John soon after made some devastating career choices, packed on a few extra pounds, and suddenly was a has-been. Until Quentin Tarantino cast him in "Pulp Fiction," he seemed destined to a life of talking baby movies.

But could Quentin keep the original JT on track? His latest effort — providing the voice for a dog in the animated film "Bolt" that opens today — could get his career racing again. But Travolta has surprised us before. Check out the dizzying highs and devastating lows in our John Travolta Career EKG.

See our John Travolta EKG FlipBook here.

Welcome Back, Kotter, 1975-1979

EKG reading: PALPITATIONS

Travolta taught every young suburban girl to fall in love with the not-so-bright bad boy. Who? What? Where? Why?

The Boy in the Plastic Bubble, 1976

EKG reading: PALPITATIONS

Loveable, sweet, sensitive, safe: the boy in the bubble couldn't hold your hand but could touch your heart. TV movie schmaltz at its finest.

Saturday Night Fever, 1977

EKG reading: PALPITATIONS

Travolta had it going on in "Saturday Night Fever." The white suit, great hair, suave moves on and off the dance floor, and a soundtrack to his life courtesy of the Bee Gees. Who could ask for anything more?

Grease, 1978

EKG reading: PALPITATIONS

24-year-old Travolta played an 18-year-old high school senior. But we can overlook that because Danny loved Sandy enough to change for her — and he sang the high notes in their duets.

Urban Cowboy, 1980

EKG reading: PALPITATION

Proving once again that tough guys do line dance.

Blow Out, 1981

EKG reading: MURMUR

"Blow Out" was the beginning of the end of the first half of Travolta's career. Personally, we were sucked into his performance as the sound engineer who captures a Governor's assassination on audiotape, but others called the film misogynistic. The box office numbers were dismal, and John's career took a near fatal hit.

Staying Alive, 1983

EKG reading: FLATLINE

Never has a good movie had such a bad sequel. This "Saturday Night Fever" follow-up was a raging misstep. You know it's bad when the highlight is a theme song by Frank Stallone (remember "Far From Over" anyone?).

Perfect, 1985

EKG reading: FLATLINE

Even though he was still young and fit, Travolta doing aerobics was not a pretty sight. Not a great movie either.

Look Who's Talking, 1989

EKG reading: MURMUR

When you start making movies where you talk to animals or babies — and they talk back - you know your career has hit a major pothole.

Pulp Fiction, 1994

EKG reading: PALPITATIONS

Travolta really does owe the second half of his career to Quentin Tarantino. Quentin shoved that syringe straight into John's failing heart and started the beat all over again.

Get Shorty, 1995

EKG reading: PALPITATIONS

Travolta lampoons the industry that had been so kind and so cruel to him through the years.

Michael, 1996

EKG reading: ARRHYTHMIA

This sounds like a bad movie — Travolta plays a rough-around-the-edges angel — but there's a surprising charm to the film.

Mad City, 1997

EKG reading: FLATLINE

John Travolta and Dustin Hoffman verbally sparring on-screen for about two hours: this movie should have been called "Bad City," because that's what it was — really, really bad.

Face/Off, 1997

EKG reading: MURMER

You have to completely suspend your disbelief for this one. Travolta and Nicolas Cage have surgery and literally trade faces. Then they play each other in an action-packed thriller that's mildly entertaining.

Primary Colors, 1998

EKG reading: ARRHYTHMIA

Travolta takes a turn as a Southern governor running for President and joyfully impersonates Bill Clinton.

Battlefield Earth, 2000

EKG reading: FLATLINE

John fought long and hard to get Scientology guru L. Ron Hubbard's sci-fi thriller made into a big budget film. And those who went to see it fought long and hard to make it through to the end. This isn't even an it's-so-bad-it's-funny movie. It's just bad.

Swordfish, 2001

EKG reading: MURMUR

Not a great movie and an even worse haircut, but after Battlefield Earth anything that Travolta did that was not Battlefield Earth 2 could only be a step in the right direction.

A Love Song for Bobby Long, 2004

EKG reading: FLATLINE

This movie should have been called "A Long Song for Bobby Long." It was slow and boring.

Wild Hogs, 2007

EKG reading: FLATLINE

Seemed like an excuse for Travolta and his buddies to ride around on motorcycles for a few months. The tagline: "A lot can happen on the road to nowhere" should have ended with "but that doesn't mean you're going to enjoy watching it."

Hairspray, 2007

EKG reading: PALPITATIONs

Travolta is back on top doing what he does best — singing and dancing — even if he did have to dress like a woman to do it.

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