The more I research it, the more it becomes quite clear that I'm lucky to remember The Knights of the Galaxy. This futuristic star-spanning assembly was the brainchild of Robert Kanigher (under the name of "Anthony Dion") and Carmine Infantino for the earliest 1951 issues of Julius Schwartz's Mystery in Space. This comic is most famous for the long-running Adam Strange series but that was now how it began.
Lyle and the Knights of the Galaxy seemed modeled on the tried and true Flash Gordon motif so elegantly designed by Alex Raymond decades before. A handsome blonde hero saving a comely gal with the stars as a backdrop is the very essence of vintage sci-fi.
I read a Knights story in Justice League of America #91 and as it turns out that was only one of two stories about the team reprinted by DC at the time, other was in JLofA #85. That's odd since they were quite content to reprint most things more than a few times, especially with the 100-pagers they were soon to publish. To my knowledge this team's stories, which total eight have never been collected together in a trade.
The Arthurian motif was also used by DC with the much more famous Atomic Knights, a group of stalwarts on a blighted Earth. The Knights of the Galaxy cleave to the classic legend which inspired them much more closely as Merlin even makes an appearance in a later tale. The team appeared on the covers of the first six issue of Mystery in Space before giving way in the seventh. They only ever appeared in two more stories beyond that. Here is a site which discusses the stories with some neat glimpses of Infantino's art.
Here are those covers. Enjoy!
A Knights story was reprinted in this collection from 1999 which sports a vivacious Mitch O'Connell cover.