Heo Young-saeng (Korean: 허영생; born: November 3, 1986) is a South Korean entertainer. He is the vocalist of the boy band SS501. He's also the leader of Double S 301.

In 2010, Heo left DSP Media, who managed him as part of SS501, and moved to B2M Entertainment, with bandmate Kim Kyu-jong, to pursue his solo career. His debut album as a soloist entitled Let It Go was released in May 2011. He then released several albums more in Korea and Japan, with the hit tracks "Crying", "The Art of Seduction", "Weak Child", and "1.2.3", among others. In 2012, Heo played his first acting role in KBS2's sitcom I Need A Fairy.

Heo has performed in musicals as well: he debuted in The Three Musketeers, playing the role of D'Artagnan during 2011, and appeared in 2013, the Summer Snow musical.

On October 31, 2013, Heo started his mandatory, 21-month military service as a police officer. He completed his military service on July 30, 2015. He also joined CI Entertainment.

In December 2015, Heo returned to theater to play the role of Han Min-ho in the musical Haru. It's together with Kim Hyung-jun. Also, it served as the musical comeback of Heo after 21-month of hiatus due to military service.

In January 2016, Heo reunited with Kim Kyu-jong and Kim Hyung-jun and grouped as Double S 301. CI Entertainment released a photo teaser for their comeback. The group released an album entitled Eternal 5 on February 16, 2016, followed by a Japanese album entitled Eternal S on April 20, 2016.