Even though Tenna’s first official appearance was in this year’s Deltarune Chapter 3, creator Toby Fox conceptualized him back in 2016, roughly a year after Undertale was released. The character went through several redesigns before becoming the lovable (and loud) game show host that fans now know him as.
Fox reveals that Tenna was the reason he was practicing 3D animation back in October 2016. Using an Xbox Kinect, he attempted to rotoscope his movements onto Tenna. As a rough walking animation was the best he could do at the time, Fox quickly abandoned the idea (he also had plans for Tenna to do MikuMikuDance-style dances using the animation program but abandoned those as well).
While Fox’s initial plan was to render Tenna in a manner similar to the characters in Capcom’s Ghost Trick: Phantom Detective, the end result ended up looking “tremendously bad” and he slowly abandoned the idea.
Tenna’s final design was the result of several artists working together. His initial design and poses were created by Fox, whereupon concept artist Gigi D.G. polished the designs and created Tenna’s turnaround (allowing the character to be seen from multiple angles). Artists Clairevoire, Everdraed, Lindsay and Alex Small-Butera, and Audrey worked on Tenna’s static sprite frames, intro, intro poses, and typography respectively. Finally, all of Tenna’s 3D animations were created by Chelsea Saunders, a.k.a. PIXELATEDCROWN.

That makes seven more artists who worked on Tenna as compared to when Fox created him all those years ago. Tenna has come a long way since Fox’s first 3D animated render of him, and all that hard work combined with Fox’s writing has made him a favorite among Deltarune fans.
Deltarune Chapters 1-4 is now available for Nintendo Switch 1 and 2, PC (macOS and Windows), and PlayStation 4 and 5.