Aloysius Yapp (/ˌæloʊˈɪʃəs/;[2] Chinese: 叶浚惟; pinyin: Yè Jùnwéi; born 2 May 1996)[3] is a Singaporean professional pool player.

In 2023, Yapp defeated David Alcaide of Spain in the final, 13-7, to win the International Open 9-Ball Championship in Norfolk Virginia, USA.

He went on to defeat both Rodrigo Geronimo and Dennis Orcollo by a scoreline of 11–6 in the quarterfinals and semifinals respectively,[10] before losing to Carlo Biado 8–13 in the final, concluding his best finish in a major tournament.

Johann Chua, Carlo Biado, Aloysius Yapp, Duong Quoc Hoang, and Ko Pin Yi make up the team, which is coached by the tournament namesake and greatest of all time Efren Reyes.

Team Europe is made up of Jayson Shaw, Eklent Kaci, Francisco Sanchez Ruiz, David Alcaide, and Mickey Krause.