Well, a recent issue of Green Lanterns introduced a Kryptonian member of the Corps. The issue involved the book's stars Simon Baz and Jessica Cruz traveling back in time a few billion years, to the early days of the Green Lantern Corps where they meet the original seven Green Lanterns, including a newly recruited Kryptonian woman by the name of Jan-Al. The issue doesn't exactly....end well for her, but it does set an interesting precedent for the "present" day. More details are in the link below.
www.cbr.com/green-lantern-first-kryptonian-gl/ 
