Michael Boyle

While the action genre is filled with big tough guys like Jack Reacher (Alan Ritchson), what sets him apart is his total absence of family or possessions. Reacher has no wife or kids, nor does he have a home or car. He is a self-described "hobo" by choice, roaming through the country with nothing except a toothbrush. "Reacher" author Lee Child thinks this is a key part of the character's appeal.

Cop dramas have existed from virtually the moment television began. "Barney Blake, Police Reporter," premiered in 1948 and embraced a crime-of-the-week formula that would become a staple of the genre. "Stand By For Crime" premiered in 1949; Whereas the previous show established a key trend, this one's approach was a bit of a dead end. The series aired for a live audience, and invited viewers to call in with their own guesses as to who the killer was.

Four years before Gary Sinise played a hero in the hit Stephen King miniseries "The Strand," he guest-starred as a serial killer suspect in the Los Angeles-set NBC cop series "Hunter," which aired over 150 episodes across seven seasons between 1984 and 1991. Sinise appeared in the Season 6 episode "Lullaby" as Lord Tony Rutherford, a British politician and keen photographer suspected of killing multiple sex workers from his home country. It was one of his first notable roles, yet nobody really talks about it these days, and that's a little surprising, because "Hunter" was a pretty big deal at the time.

"Reacher" may have made Alan Ritchson a major star, but the actor was already quite busy long before the Prime Video series. Even outside of the major roles on this list, he's landed a series of charming one-off roles. He starred in the "Black Mirror" episode "Nosedive," as the handsome, potentially closeted groom of the main character's childhood frenemy; played Jess'(Zooey Deschanel) love interest, Matt, in Season 4 of "New Girl;" and a talking cow in an oddly psychedelic episode of the Nickelodeon series "Fred."

“Can we even trust her?” Stewart asked.

“Can we even trust her?” Stewart asked. Jon Stewart called out President Trump's scandalous relationship with his 35-year-old aide Natalie Harp.

Why was Pete Campbell so miserable on Mad Men? Vincent Kartheiser explains the character's lack of purpose and why his search for happiness took so long.

Throughout Season 4 of "Reacher," Elspeth Sampson's actress, Kathleen Robertson, might seem familiar to you due to her past roles on "Beverly Hills, 90210" or "The Expanse." But you might also recognize the actress from her major role on the Starz drama "Boss."

Timothy Olyphant often plays cool, smooth-talking characters, but he changed things up in his sole episode of "My Name is Earl." The popular (though short-lived) 2005 sitcom introduced Olyphant as a side character named Billy. From his first scene, Billy is established as the sort of lowlife who'd happily peer pressure an eleven-year-old into gambling away his father's car. He successfully wins a race against child Earl (Noah Crawford) and takes his father's Mustang, destroying Earl's relationship with his dad for the rest of his childhood.

It's easy to forget, but there was a time when Danny DeVito's Frank Reynolds was not a main character on "It's Always Sunny in Philadelphia." There were only four members of the Paddy's Pub gang in the show's low-budget, seven-episode first season.