Fans of The Walking Dead and Legend of Korra rejoice: Steven Yeun, known to fans of the AMC horror show as Glenn, will be joining the voice cast of the Nickelodeon animated series for a guest role as Wan, the very first Avatar in existence. Yeun's character will appear in two episodes titled "Beginnings 1 & 2" during the second season – aka Book 2: Spirits – debuting later this year.

The sequel to the beloved Avatar: The Last Airbender, *Legend of Korra *debuted last April to 4.5 million viewers, and quickly became the highest-rated show on Nickelodeon. Both series are set in a fictional world where people called "benders" have special abilities that allow them to control one of the four elements (water, earth, air, and fire), but only one person – the Avatar – can control all four and bring balance to the world.

Wan's story will take place 10,000 years before Korra's time, and follow the teenage explorer and skilled bender as he tries to bring balance between mankind and the spirits, a quest that ultimately leads to becoming the first Avatar.

Steven Yeun (Photo by Richard Shotwell/Invision/AP)

Legend of Korra co-creator and executive producer Bryan Konietzko told Wired that they cast Yeun in part because of the versatility of his voice acting, and how it aligns with the narrative journey of Wan throughout those two episodes.

"Steve's vocal quality and acting can range from an innocent, naïve young man, to a trickster anti-hero, and all the way to a full-fledged action hero," said Konietzko. "And in each take, he made Wan really human and relatable, despite the mythic setting of his tale."

While Avatar: The Last Airbender established a long tradition of Avatars that stretched indefinitely into history, this will be our first look at the first person to take on (or create) the mantle of the Avatar, a reincarnated role that passes to one person in each generation to serve as the human incarnation of the planet.

These episodes will also mark a significant stylistic departure from the usual aesthetics of Legend of Korra. "To depict the world in Wan's time, the creative team drew inspiration from ancient and traditional East Asian ink wash paintings and woodblock prints for the environments, color palettes, and stylizations of the elements," said a Nickelodeon representative. "The results expand the vision of the Avatar world, but also stay very true to the building blocks of its visual influence."

More details will be announced at the Legend of Korra panel at Comic-Con International in San Diego, which is slated for 11:15 a.m. Friday morning in Ballroom 20. Check out the WIRED liveblog for up-to-the-minute details on the event, which opened today to the general public.