Hongjoong is described as Ateez’s leader in Wikipedia’s history section.
His connection to the group began before Ateez officially existed. KQ Entertainment reportedly discovered a letter and sample mixtape from Hongjoong, who wanted to become a trainee. He became the company’s first official trainee and was later joined by Yunho and the other members who formed the group.
Hongjoong also contributed creatively before debut. The pre-debut group KQ Fellaz released “From,” a song composed and produced by him, during their American training web series. That early songwriting and leadership role helped establish him as more than just a performer.
Ateez’s leader is sometimes confused with members known for especially prominent performance roles. San is widely recognized for his expressive stage presence, Yunho for his dancing, and Seonghwa as one of the group’s eldest members. None of those distinctions changes the leadership answer: Hongjoong is the member identified as the group’s leader.
He officially debuted with the rest of Ateez on October 24, 2018, when the group released Treasure EP.1: All to Zero.