Liam Neeson may be the world's most improbable action star.

The towering 59-year-old star of The Grey, known earlier in his career for roles in critically-lauded films such as Schindler's List and Kinsey, has turned into one of the most reliable action stars. And he did it at an age when contemporaries such as Denzel Washington and Bruce Willis have become less of a sure thing in action movies.

The former forklift operator from Northern Ireland also delivers at least as well -- or better -- than younger stars such as Matt Damon, Vin Diesel and Nicolas Cage in those movies. His mid-life transformation, which began with 2008's Taken, has continued after the 2009 death of his wife Natasha Richardson in a skiing accident.

In The Grey, Neeson plays a man working on an oil field in Alaska who must survive the elements and a pack of wolves after a plane crash. The movie opened last weekend to $20 million at the domestic box office, exceeding expectations.

Last year, Unknown grossed $61.1 million domestically on a budget of $30 million.

Taken -- the movie that turned the Academy Award-nominated actor into an action star -- grossed $145 million domestically on a $25 million budget in 2008.

Of his recent action movies, The A-Team was a disappointment, grossing $77.2 million domestically on a $110 million budget in 2010. But it was a ensemble adaptation of a TV show that did not rest on Neeson's shoulders or play to his strength as middle-aged man with something to prove.

Now look at action films starring Washington, a close contemporary to Neeson at 57, and once a go-to action star. Universal is opening his next movie, Safe House, on February 10.

His 2010 Unstoppable grossed $81.6 million domestically on a budget of $100 million. The Book of Eli, in 2010, took $94.8 million on an $80 million budget. The Taking of Pelham 1 2 3 in 2009, grossed only $65.5 million domestically on a $100 million budget.

Willis has seen his star power diminish from his heady days heading the Die Hard franchise. Now 56, a few years younger than Neeson, he has an uneven record at the box office, with Red and Cop Out among his recent offerings.

Damon is a generation younger at 41. His Bourne movies made him an action star, but he doesn't seem to have a big appetite for such meat-and-potato roles, choosing instead to star in a diverse array of films including We Bought a Zoo, True Grit and Hereafter.

The 2007 The Bourne Ultimatum alone grossed $227 million domestically on a $110 million budget.

But Contagion, in 2011, grossed $75.6 million domestically on a budget of $60 million, the 2010 The Green Zone took $35 million domestically on a $100 million budget and 2011's The Adjustment Bureau took $62.5 million domestically on a budget of $50.2 million.

It's the same for Diesel.

While he is golden in Universal's spectacularly successful Fast and Furious franchise, the 44-year-old otherwise doesn't seem to be a bankable action star outside that.

He had good numbers with his 2005 The Pacifier, which grossed $113 million domestically and had a budget of $56 million. But his 2008 Babylon A.D. grossed only $22.5 million domestically on a $70 million budget. His 2004 The Chronicles of Riddick took only $57.6 million on a budget of $110 million and his 2003 A Man Apart grossed only $26.2 million domestically on a $36 million budget.

At 59, Neeson was born the same year as David Hasselhoff, Gus Van Sant, Mandy Patinkin, Dan Aykroyd, John Goodman, Harvey Fierstein and one-time action star Mr. T.

And before he was an action star, he was an actor. He was nominated for an Academy Award and a Golden Globe for his role as Oskar Schindler in Schindler's List, and was nominated for a Golden Globe for his roles in Kinsey and Michael Collins.

The action roles keep coming for him: In addition to a small role in The Dark Knight Rises, this year he stars as Admiral Shane in Battleship and as Zeus in Wrath of the Titans. He will also return as Bryan Mills in a sequel to Taken, the movie that made him an action star.