Credit: ABC Photo: Demi Lovato on Grey's Anatomy

As casting decisions go, Grey's Anatomy has a pretty good track record. We've seen a ton of quality acting from series regulars and guest stars alike. But sometimes the casting or the writing just doesn't do a character or actor justice. So let's review the best and worst of Grey's stunt casting!

Eric Stoltz is a film and TV actor known for such movies as Pulp Fiction and Some Kind of Wonderful, but he's also notable for being the original Marty McFly in Back to the Future before Michael J. Fox replaced him. In addition to directing multiple episodes of Grey's, Eric also appeared as a death-row inmate (William Dunn) who tried to bash his own head in after brain surgery to avoid lethal injection and to give his organs to a young patient in need. Plus, he was majorly creepy. Grade: B+

Either you know Christina Ricci from her roles as a kid in The Addams Family or Casper or from her role as an adult in ABC's new TV series Pan Am. On Grey's, she played Hannah Davies, a young paramedic who stuck her hand inside a patient to stop the bleeding, not realizing that she was also touching a homemade bazooka. She had a major freak-out and fled the scene, leaving Meredith (Ellen Pompeo) to take her place. Sounds straightforward enough, yes, but Ricci's acting was the best we've seen from her. Grade: A

As a recording artist, Mandy Moore's pop-star-status has fizzled. But as an actress, she's still shining. She's had memorable roles in A Walk to Remember, Saved!, and Because I Said So. On Grey's, she played Mary, one of Miranda Bailey’s (Chanda Wilson) favorite patients who had the misfortune of being at the hospital during the shooting. Though she survived that day (and saved Bailey's sanity), a rare condition caused her to fall into a coma during her next surgery and later die. Definitely a tear-inducing moment! Grade: B

Faye Dunaway is an Oscar-winning actress best known for movies like Chinatown, Network, and Bonnie and Clyde. On Grey's, she portrayed Margaret Campbell, a legendary surgeon who was royalty at Seattle Grace until one foolish mistake convinced her that it was time to retire. Good stuff, but we wanted to see some Oscar-worthy scenery-chewing! Grade: C

Credit: ABC Photo: Mandy Moore on Grey's Anatomy

Demi Lovato is a singer/songwriter and an, ahem, "actress" best known to the Disney demographic. On Grey's, she played a young girl whose freak-outs were attributed to schizophrenia but were later determined to be a result of a hole in her inner ear. Now, I'm sure there are folks who think that Demi is a fantastic actress, but in our minds, her involvement just reeks of a ratings ploy. Grade: D (for Demi!)

Kyle Chandler is forever ingrained in the hearts of TV fans as the star of Friday Night Lights. On Grey's, he portrayed the head of the bomb squad (Dylan Young) that responded to the grenade-in-chest situation. Not only did he radiate calmness, making sure everyone kept as calm as possible, he looked damn good doing it. Never mind the fact that he exploded; he even reunited with Meredith during her short foray into the afterlife! Grade: A

A notable ginger, you might recognize Seth Green from his roles on Buffy the Vampire Slayer and the Austin Powers trilogy. On Grey's, he played Nick, a man whose carotid artery was left nearly exposed by a tumor excision. His sunny demeanor and quick wit charmed the pants off both us and Lexie, but then his vein blew. And that blew! Grade: A-

Diahann Carroll broke boundaries with her starring roles in shows like Julia and Dynasty. On Grey's, she played Mama Burke, i.e. Burke's mom.  For a while, she seemed like in-law-zilla, controlling every aspect of Burke and Cristina’s (Sandra Oh) wedding, even Cristina's eyebrows.  But years later, she returned to tell Cristina that she admires her and her ambition. We appreciate the dimensionality. Grade: B

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Grey’s Anatomy airs Thursdays at 9 pm ET/PT on ABC.

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