Early life Mack was born in Preetz, Schleswig-Holstein, Germany to American parents, Mindy and Jonathan Mack. Her father was an opera singer performing there. The Mack family moved back to the United States when she was two years old. She is the middle of three children with an older brother Shannon and a younger sister Robyn.
CareerShe began her acting career at the age of four in commercials for "German Chocolate". Mack then went into modeling for a short period because her mother thought she "looked cute in clothes". She began studying at The Young Actors Space in Los Angeles when she was seven.
Her first major television role came in an episode of the WB series 7th Heaven, in which she gained a lot of attention playing a teenager who cut herself. In 2000, she starred in the short-lived series Opposite Sex. She also starred opposite her former Smallville castmate Sam Jones III in an R. L. Stine miniseries The Nightmare Room. Her filmography includes Eric Stoltz's directorial debut My Horrible Year!, in which she plays a girl having great difficulties in her life as she turns sixteen, and Camp Nowhere.
In October 2001, Mack began starring as Chloe Sullivan, one of Clark Kent's best friends, in the CW hit series Smallville. The character of Chloe Sullivan was an original character created solely for the TV show, never before in the Superman franchise and quickly became a fan favourite. The character's popularity (largely due to Mack's portrayal of her) eventually led to Chloe being introduced into DC Comics in 2010. Mack was constantly praised for her portrayal of Chloe Sullivan and has earned several awards and nominations for it.
In the summer of 2006, Mack voiced the sister of the main character in the Warner Bros. CGI movie The Ant Bully. That year she also provided the voice of a museum curator named Clea in an episode of The Batman.
In November 2008, Mack made her directorial debut with the Smallville in season 8: episode 13 titled "Power", which aired January 29, 2009.
Since May 2009, Mack has been part of a project with the Iris Theatre Company which performed a piece of experimental theater at the Prague Fringe Festival.
She voiced Power Girl in the Warner Premiere animated feature, Superman/Batman: Public Enemies, released on September 29, 2009.
In May 2010 it was announced that Mack will not be appearing as a series regular on the final season of Smallville, but will return for several episodes. At the 2010 San Diego Comic Con it was mentioned that Mack may still be considered a series regular, as she would appear in several episodes. Mack returned for five episodes in the tenth season, being billed as a series regular for the episodes she appeared in. She also eventually appeared in the two-part series finale.
It was announced in March 2012 that Mack was cast in the television series Wilfred in a recurring role in the second season. She played the love interest for the lead character Ryan, played by Elijah Wood. Mack further returned to Wilfred in its final season for one episode.
On November 22nd 2014, it was reported that Mack had been cast in an episode of FOX TV show The Following. She will play the role of a police officer named Hilary and will appear alongside former Smallville alumni Shawn Ashmore and Kevin Bacon. Furthermore, according to her official Twitter account, Mack has also lent her voice to a new cartoon for Amazon.