Filmography [ ] Film [ ] Year Title Role Notes 2004 Date in 'Blood Prom' 2006 Deora Frances Bodley 2010 Gail 2010 Sunny 2010 Vacation Donna 2013 Allie 2015 Nicki 2016 Almost There Natalie 2017 Alison 2017 Jennifer 2017 Amber 2019 Liz Koch Television [ ] Year Title Role Notes 2006 Gloria Kulhane Episode: "Class" 2008 Molly McConnell Main cast 2009 Sonja Episode: "The Tommy Brown Affair" 2009 Valerie Boone Episode: "Midnight" 2009 Sophia Episode: "The Case of the Beautiful Blackmailer" 2011 Lori Lynn Episode: "Walker Down the Aisle" 2013—2015 Siobhan Kelly Main Cast seasons 1—3 26 episodes 2013 Margot Dixon Recurring character 2014 Elizabeth Farrell Recurring character 2015 Amanda Marcassin Episode: "Innocents" 2015—2020 Allison "Allie" Knight Recurring character 2016 Rachel Episode: "Palpating the Orbital Rim" 2016 Captain Taylor Mathison Episode: "The Woman in 8D" 2018 Theresa Oakes 2 episodes 2018 Sophie Bishop Episode: "An Infinite Capacity for Taking Pains" 2018 Elliott Episode: "Big Little Chill" 2019 Sierra Thompson Recurring character References [ ]• Career [ ] Dunn first rose to prominence on the FOX TV series as Molly McConnell opposite.