<P> Although originally introduced as a recurring character in the season premiere, trauma surgeon Dr. Owen Hunt was promoted to a series regular in the fourteenth episode of the season "Beat Your Heart Out". He was portrayed by Kevin McKidd and was conceived as a love interest to resident Cristina Yang . Originally only signed onto the show until December 2008, Kevin McKidd was upgraded to regular status after appearing in five episodes . Shonda Rhimes said, "I am excited to have Kevin McKidd joining us for the season, he's been a delight to collaborate with and brings incredible passion, talent and creativity to his work ." Weeks after Hunt's first appearance on the show, Matt Roush of TVGuide comments that "Hunt / McKidd is the most encouraging thing to happen to Grey's Anatomy in quite a while ." Robert Rorke of the New York Post states that McKidd was brought in as Hunt to "boost the sagging fortunes" of the show's ratings . Kelley L. Carter of USA Today, describes Hunt as "hardcore" and "the antithesis of the other males on the show ." </P> <P> Numerous supporting characters have been given expansive and recurring appearances in the progressive storyline, including: Melissa George as Sadie Harris, Kimberly Elise as Dr. Jo Swender, Jessica Capshaw as Dr. Arizona Robbins, Amy Madigan as Dr. Wyatt, Mary McDonnell as Dr. Virginia Dixon, Eric Stoltz as William Dunn, Jennifer Westfeldt as Jen Harmon, Ben Shenkman as Rob Harmon, Shannon Lucio as Amanda and Samantha Mathis as Melinda . Jeffrey Dean Morgan reappeared as the deceased Denny Duquette in Izzie's hallucinations due to a brain tumor . Former series regular Kate Walsh returned to the show with a special guest star billing as Dr. Addison Montgomery along with fellow Private Practice stars Audra McDonald portraying Naomi Bennett, Taye Diggs in the role of Sam Bennett and Grant Show portraying Dr. Archer Montgomery . Tyne Daly also appeared receiving a special guest star in the role of Carolyn Maloney Shepherd, Derek's mother, while Héctor Elizondo appeared as Carlos Torres, Callie's father . </P> <Ul> <Li> Ellen Pompeo as Dr. Meredith Grey </Li> <Li> Sandra Oh as Dr. Cristina Yang </Li> <Li> Katherine Heigl as Dr. Izzie Stevens </Li> <Li> Justin Chambers as Dr. Alex Karev </Li> <Li> T.R. Knight as Dr. George O'Malley </Li> <Li> Chandra Wilson as Dr. Miranda Bailey </Li> <Li> James Pickens Jr. as Dr. Richard Webber </Li> <Li> Sara Ramirez as Dr. Callie Torres </Li> <Li> Eric Dane as Dr. Mark Sloan </Li> <Li> Chyler Leigh as Dr. Lexie Grey </Li> <Li> Brooke Smith as Dr. Erica Hahn (Until Episode 7) </Li> <Li> Kevin McKidd as Dr. Owen Hunt </Li> <Li> Patrick Dempsey as Dr. Derek Shepherd </Li> </Ul> <Li> Ellen Pompeo as Dr. Meredith Grey </Li>

What happens in grey's anatomy season 5