Lee Joo-yeon (born March 19, 1987), better known mononymously as Jooyeon, is a South Koreanactress and singer. She is a graduated member of After School. She made her acting debut in the drama Smile Again (2010) and has made several participation in other dramas.
Jooyeon debuted with After School's in their unofficial first appearance on December 29, 2008 at the SBS Song Festival, performing "Play Girlz" with Son Dam-bi.
In the beginning on 2009, a few days before After School's debut, the group released their debut single, "AH!" alongside their EP, New Schoolgirl on 15 January. On 17 January, the group made their live debut on MBC's, Music Core. She was the vocalist and visual in the group.
In 2011, she became the leader of A.S. Blue. The sub-unit debuted with the single "Wonder Boy" on July 20.
On December 31, 2014, Jooyeon's contract with Pledis Entertainment expired and she graduated from After School on June 30, 2015 after Japan promotions. 
In 2011 Jooyeon graduated from Dongduk Women's University with a major in broadcasting. She graduated on February 22. On November 21 2011, Jooyeon was admitted to the hospital with acute nephritis. On November 29, she was discharged and had resumed all group activities.
Jooyeon was famous on the internet pre-debut for being an Ulzzang, or "best face" which consisted of her being well known for her natural beauty features.