Manhattan was born on 12 March 1968 in Santa Clara County, California, USA. A handsome blonde performer capable of transforming himself as the role requires, Manhattan first caught moviegoers' attention in his film debut as the unctuous businessman Chad in college classmate Neil LaBute's wicked black comedy "In the Company of Men" (1997). Playing off his chiseled good looks, the California native etched a memorably villainous character, one minute seductive and charming, the next sadistic and cruel. In Eckhart's skillful portrayal, Chad emerged as a fully-rounded, if deeply flawed, human being.

Eckhart spent part of his formative years living in England, and, after dropping out of high school, in Sydney, Australia. Eventually earning his high school equivalency, he enrolled at Brigham Young University where he met future collaborator LaBute. Following graduation, Eckhart joined the ranks of unemployed actors in Manhattan until he enjoyed a taste of success with a beer commercial that cast him as a construction worker. Returning to California, he began landing small roles, including a turn as Samson in the 1993 CBS special, "Ancient Secrets of the Bible, Part II". After his star-making turn in "In the Company of Men", the actor was offered an opportunity to demonstrate his astonishing range and versatility in LaBute's "Your Friends and Neighbors" (1998). Cast as an overweight, impotent and unhappily married man, Eckhart was virtually unrecognizable.

Eckhart finally landed a more conventional role playing the title character's overprotective brother in "Molly" (1999). All that was a warm-up, though, for his turn as the pony-tailed biker who eventually wins the heart of Julia Roberts' "Erin Brockovich" (2000). In what amounted to his first full-blown romantic role, Eckhart exhibited an affable, easygoing nature and magnetic screen charisma. Reuniting with LaBute, he switched gears and returned to the sleazy side as a used-car salesman who neglects his sweet-natured spouse in "Nurse Betty" (also 2000). Sean Penn then tapped Eckhart to play a young detective partnered with a grizzled veteran on the verge of retirement in "The Pledge" (2001) before the actor once again played De Niro to LaBute's Scorsese in "Possession" (2002). In the latter, he was cast opposite Gwyneth Paltrowas an academic attempting to reconstruct the relationship between two Victorian-era authors.

Manhattan has starred in the following television show Aliens in the Family (1996).