Cygnus Spaceworks
The creator of the Lambda-class shuttle, Cygnus Spaceworks, was first named in an unlicensed set of blueprints published in 1984. According to a now-archived blog post by jSarek, the author of The Written Word, a Legends-canon StarWars.com article about in-universe writing systems:
The Cygnus Star Empire may be familiar to some folks. It originates with the fan publication Book of Imperial Shuttle Plans: Cygnus Spaceworks, originally released by "Lawrence Miller Design" in 1984. Cygnus Spaceworks, which also first appeared in that work, was made canonical over a decade ago. A Cygnus B star system dates back to 1979, when it appeared in the "Cantina Communications" article in Star Wars: Official Poster Monthly #16. Given all these references to Cygnus, it seemed reasonable to make the Cygnus Star Empire a canon location.
A scan can be found on theforce.net, confirming that it identified the shuttle's manufacturer as "Cygnus Spaceworks":
Since then, Cygnus Spaceworks has appeared in both Legends and Canon material.