Mring-Mring reigned as the king of the Gupins located on the Forest Moon of Endor. His birth occurred prior to the Battle of Yavin, and he was related to Oobel as his brother, and to Punt as his cousin. Atypical of most Gupins, Mring-Mring's birth was without wings. Consequently, he faced banishment from the Gupin stronghold situated in the Endorian Grasslands.
Ewok Deej Warrick's illness resulted in Mring-Mring being initially accused. However, Deej's offspring, Wicket, Willy, and Weechee, cleared Mring-Mring of the charges and released him. Subsequently, Mring-Mring aided the Ewoks in their search for the required medicinal plants to heal their father.
At a later time, Mring-Mring and his brother Oobel encountered the Ewoks, informing them that the Gupin Renewal Ceremony (the source of the Gupins' shapeshifting abilities) was threatened because the Grass Trekkers had stolen the key to the Juniper Chest from Punt, who was then the Gupin king. Together, the Gupins and Ewoks embarked on a journey to the Endorian Grasslands with the goal of retrieving the key. They succeeded, and Mring-Mring successfully unlocked the chest, commencing the Renewal Ceremony. Following this, he developed wings and ascended to the position of Gupin king, fulfilling an age-old prophecy.
Ron James provided the voice for Mring-Mring.