Taeyeon ( born March 9 , 1989 ) , real name Kim Tae-yeon , is a South Korean singer , and leader of the nine-member girl group Girls ' Generation . Kim Tae-yeon ( ; Hanja : é ` å å ; born March 9 , 1989 ) , commonly known as Taeyeon , is a South Korean pop singer , actress , and spokesmodel . She is the leader of the Korean nine-member girl group Girls ' Generation , formed by SM Entertainment in 2007 .