From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The Tsufruian King is the king of the Tsufruians.
Dragon Ball GT
The Tsufruian King was seen and mentioned in a flashback that Baby had during Dragon Ball GT. The Tsufruian King was the last of their kings to exist and apparently used an advanced machine to combine his body and DNA with the genetic experiment known as Baby in order to extract vengeance for his people. Prior to his peoples' final eradication by the Saiyans near the end of the Saiyan-Tsufruian war, Baby was launched into space to escape the planet's destruction with the remnants of the Tsufruian King along with him. Although the Tsufruian King was only seen in Dragon Ball GT, chronologically he would have existed before the start of Dragon Ball, but was never mentioned in Dragon Ball or Dragon Ball Z. He is presumed to have existed even though he was not mentioned in the history of the Tsufruian people as described by North Kaio in both Dragon Ball Z and Dragon Ball Z Gaiden: Saiya-jin Zetsumetsu Keikaku.