Kelk Ronso is the leader of the Ronso, and a Maester of Yevon in Final Fantasy X. Kelk has human-like speech and sophisticated mannerism, quite unlike the broken English spoken by most other Ronso.
Kelk is in charge of administering Spira's judicial system and puts summoner Yunaand her guardians on trial for the murder of Maester Seymour. He is the only one of the Maesters unaware that Seymour had killed his father, Jyscal, and learning it troubles him. Following Yuna's sentencing, Kelk has had enough with Yevon's hidden secrets and betrayals, and returns to Mt. Gagazet hoping to find honesty and order in his mountain home.
When Yuna and her guardians reach the Mountain Gate, Kelk denies them passage up the sacred mountain because of their interactions with the Al Bhed and Yevon. Upon realizing Yuna is willing to sacrifice herself for the good of Spira even after turning her back on Yevon, he praises her resolve, and lets them pass.
Shortly after, Seymour advances the mountain intent on continuing his mission to become Sin. Kelk had promised Yuna and her guardians he and the Ronso would bar the path of any intruders wishing them harm. When Seymour is prevented passage he slays every Ronso in his path, including Kelk.