The Mythrol were a sentient humanoid species with amphibious traits.
The Mythrol had amphibious traits such as gills and fins on their heads. They had thoraxes which had to be "evacuated" and could molt. Young Mythrol could produce a sweet musk. After molting, their faces would become barbed. Mythrol at a younger age were referred to as "fledglings."
They could even live for a few hundred years.
Around 200 BBY, towards the end of the High Republic Era, a Mythrol male worked as a chef for President Jamie Brasen at his estate on the planet of Begamor.
Prior to 9 ABY, a fledgling Mythrol was in the employ of Magistrate Greef Karga on Nevarro, before he stole from him and fled. Sometime later, he resided on the ice planet Pagodon within a bar, where he was harassed by a group of trawlers until the Mandalorian bounty hunter Din Djarin entered. After dealing with the trawlers, Djarin captured the Mythrol and turned him over to the Bounty Hunters' Guild. Sometime later, the Mythrol was allowed by Karga to work off his debt to him through three hundred and fifty years of indentured servitude. During that time, he aided Karga, Din Djarin, and Marshal Carasynthia Dune in infiltrating and destroying a remnant Imperial base.
In 35 ABY, the post-fledgling Mythrol Junn Gobint managed fuel supplies for the Resistance during their war against the First Order.
The Mythrol species first appeared in Chapter 1 of Jon Favreau's 2019 Disney+ television series The Mandalorian, which aired on November 12, 2019. While writing the visual dictionary for the 2019 film Star Wars: Episode IX The Rise of Skywalker, Lucasfilm Story Group member Pablo Hidalgo made a connection between The Mandalorians Mythrol and the similar looking background alien Junn Gobint in Episode IX. Taking the television character's background as a "fledgling" into account, Hidalgo established in the dictionary that the independently designed aliens belonged to the same species.