K'inich Yo'nal Ahk I (Mayan pronunciation: [kʼinitʃ joːnal ahk]), also known as Ruler 1, was an ajaw of Piedras Negras, an ancient Maya settlement in Guatemala. He ruled during the Late Classic Period, from 603–639 AD. It has been proposed that he began a new dynasty at Piedras Negras, following years of ineffective kings. The manner in which K'inich Yo'nal Ahk I came to power is largely unknown, although it is known that he waged several successful wars against Palenque and Sak Tz'i'. He was succeeded by his son, Itzam K'an Ahk I, in 639 AD. K'inich Yo'nal Ahk I left behind several monuments, including stelae at Piedras Negras and a large mortuary temple now known as Pyramid R-5.