Over the years, Jack Kirby worked on a lot of westerns, as he did most every other genre. His best known work in the genre is probably his Kid Colt, Outlaw covers for Marvel in the early 60s, and Boy's Ranch, produced with long-time partner Joe Simon.
For me, the greatest western work from The King was, again, partnered with Joe Simon for their Mainline publishing company, and later Charlton - Bulls Eye. For primary evidence, allow me to submit the fabulously designed covers for the 7 issue run. #5 is probably one of my all time favorite designs for any cover.
Simon & Kirby were rocking the west with this series. If those covers aren't enough to convince you, let's go to issue #3 (as we so often do) and take a look at the lead tale. Let me say right up front, this should be a genre, not just something we get on very rare occasions, like here and Valley Of Gwangi.
But, moving right along...
Bulls-Eye - the cowboy equivalent of a superhero, from fashion sense to story encounters. Only seven issues, and Jack didn't draw as much as i'd like - sometimes just the splash for a story - but i just dug him. And Kirby seemed to have fun with him, as in this sketch:
Now, here - go have some fun and color that groove-tastic cover from #5 yourself:
BullsEye by Simon & Kirby (1954-1955)