The moustachioed hard-man has over 300 film and TV credits under his belt, as well as - perhaps more surprisingly - a string of successful LA restaurants. But did you know that before he became known for playing hard-as-nail criminals on the silver screen, he actually was one in real life?
He's known today for his tough appearance, including a face riddled with scars from a mixture of acne and fighting, but in his youth, he was far better known for his apparent inability to stay out of trouble, and as a result, prison.
During his early years, Trejo spent a considerable amount of his time in youth detention centres all over California. These included Folsom, Soledad and San Quentin, where he became a celebrity of sorts thanks to his impressive knack for kicking the shit out of his fellow inmates.
"I was lightweight or welterweight champion of every penitentiary I've been in," Trejo told TMZ. "And I've been in all of 'em."
Trejo spent 11 years in and out of prison during the sixties for armed robberies and drug-related offences, but his life of crime came to its peak when he was placed in solitary confinement for throwing a rock at a prison officer's head during a riot. The penitentiary boxing champ was told that, if convicted, he would face the death penalty.
"I was throwing it at a group of guys and he happened to be hit," Trejo explained in a Guardian interview in 2012. "So we all had gas-chamber offences, and we were taken to the hole and I remember saying: 'God, if you're there, everything will turn out the way it's supposed to. If you're not, I'm fucked.'"
Apparently, God was listening, because this scrape with death became the catalyst that would propel the Hollywood hard-nut to stardom. With no witnesses willing to testify against him, Trejo walked away from his solitary cell, narrowly avoiding a state-sanctioned execution.
This incident prompted the actor to quit booze and drugs once he was released and he quickly got to work turning his life around.
"I discovered AA and Narcotics Anonymous," he told the Guardian. "My sponsor took me to a programme called RIF - Recover, Independence and Freedom - working with teen drug addicts. Even now, kids come up and say: 'Trejo, what's up? You helped me years ago'. So that's been a blessing."
It was through one of the kids he was working with that Trejo would land his big break.
One night in 1985, the recently reformed convict got a call from one of the boys he was mentoring, asking him to come down to his place work to ensure he didn't get tempted by all the cocaine that was around on the job. On his arrival, Trejo found himself on a film set.
"It was the film Runaway Train with John Voight and Eric Roberts," he told Men's Fitness. "You have to understand that this was 1985, and on movie sets you could walk into production and cocaine lines were right there on the table. It wasn't even hidden. It was unbelievable."
It was here on the film set that he was recognised and approached by the movie's screenwriter.
"This guy comes storming across the set," he told the Guardian. "He said: 'You're Danny Trejo!' He recognised my tattoos. He'd seen me box in San Quentin, so they hired me to train Eric Roberts how to box. I learned how not to behave on a movie set from Eric Roberts. He was very demanding."
After appearing in Runaway Train, the job offers started flowing.
"I remember the first time anyone interviewed me," he told Grantland. "It was this young Chicana... out of college, real into La Raza - 'Danny, don't you feel you're being stereotyped? You're always playing the mean Chicano dude with tattoos'. So I lifted up my shirt and said, 'What are you talking about? I am the mean Chicano dude with tattoos'."
You can't argue with that.