Woo Won-jae (Korean: 우원재; born December 23, 1996), also known as Woo, is a South Korean rapper. In 2017, he released his debut single "We Are" (Korean: 시차; RR: Sicha) which had commercial success and widespread acclaim. He has released one studio album and two EPs.

In 2017, Woo participated in Show Me the Money 6, where he finished in third place. He gained a lot of popularity through the show.

Woo made his debut through releasing a single "We Are", featuring Gray and Loco on September 4, 2017. The single was meant for Woo's final 2 stage in the finals of Show Me The Money 6, but he was eliminated in the top 3 round. The song was a very huge success as it made a successful all-kill in numerous Korean charts.

On October 31, it was announced that Woo has signed with hip hop label AOMG. Following the signing, he released a single album titled "Anxiety" on November 2.

Woo released his first EP AF on November 22, 2018, with the lead single "A Fence". One of the tracks on the EP, titled "Cash", was pre-released on November 16.

Woo released his first studio album Black Out on August 18. The album included the pre-release single "Used To", which was released on August 11.

Woo released his second EP Comma on November 24.

In March 2024, it was announced that Woo has left hip hop label AOMG after his exclusive contract with them has expired. On May 31, Woo, along with Gray and Code Kunst, co-founded Duover, a new label.