Fans weren't the only ones surprised by the appearance of the cute alien currently known as "Baby Yoda." Manufacturers told CNBC that the little green creature was absent from the promotional materials they were provided ahead of the release of "The Mandalorian" on Disney+. Some had been told that the titular character, played by Pedro Pascal, would care for a child at some point during the series, but nothing more. The Child — or "Baby Yoda," as "Star Wars" fans have been affectionately calling the character — wasn't showcased in the marketing or prelaunch merchandise for the new Disney+ show because showrunners Jon Favreau and Dave Filoni didn't want to spoil his surprise appearance. In the case of this breakout star, companies such as Fifth Sun were "literally developing the moment ['The Mandalorian'] aired," said Trey Swartz, director of business development at the apparel company. After the first episode aired, companies were given some 3-D models and renderings but remain in the dark about the character's future, just like audiences.

"Baby Yoda" merchandise available on Disney's online store. Disney

It's why most fans have noticed that retailers are selling a very similar image of "Baby Yoda" on everything from T-shirts and hoodies to mugs and cell phone cases. As more episodes arrive on the streaming service, retailers will be able to provide a wider array of stylized designs for apparel, home goods and accessories. Apparel and accessories featuring the yet-unnamed creature can be found through Amazon, Zazzle, Target, Kohl's, Macy's, Hot Topic, Her Universe, Box Lunch, Design by Humans, Walmart, eBay and ShopDisney. "It's been going really well," Swartz said of Fifth Sun's sales of "Baby Yoda" merchandise. "Especially, considering the limited capacity in which we have released product. We have plans to do more. We have more product that is pending approval." Fifth Sun shared two new T-shirt designs that were recently approved and would be available online soon.

New "Baby Yoda" T-shirt designs from Fifth Sun. Fifth Sun

However, companies such as Fifth Sun are limited in what they can develop. "Once the property has lived for a little bit, you get more freedom," Swartz said. "So we can't do combinations at the moment outside the franchise." In other words, manufacturers are not currently allowed to mix and match characters from "The Mandalorian" with other "Star Wars" movies. So, for now, there won't be any T-shirts available that feature "Baby Yoda" alongside a porg or the Mandalorian next to Boba Fett.

All we want for Christmas is 'Baby Yoda'

Keeping "Baby Yoda" a secret has also means that toys, plush and other items won't be available to purchase right away. Sculpting 3-D figures, creating die casts and getting approvals for figurines can take months, said Jim Silver, CEO of TTPM, an online toy review site. In some cases, products will just go through the licensing team for approvals. However, in others, actors, directors and even the CEO of the company could get involved in the approval process. "A T-shirt can be done in a week, because that's printing," he said. "An action figure can take six months. Plush is quicker, cut and sew is much quicker, maybe a couple months."

Still from "The Mandalorian" on Disney+. Disney