Info sourced from the Graphic artists Guild Handbook
"Editorial illustrators are commissioned by designers or by art directors of consumer and trade magazines, newspapers, and online outlets to illustrate specific stories, covers, columns, blogs, or other editorial material in print or digital media." 
List of potential editorial clients:
Reader's Digest, Time, Bloomberg, Sports Illustrated, Business week, playboy, the New Yorker, Family Circle, Atlantic Monthly, New Republic, Mother Jones, MORE, Women's Health, New York Times, The Washington Post, The Wall Street Journal
Single Interest, Trade, institutional, or professional: Field & stream, Institutional Hospitals, Architectural Record
Editorial Examples
- Historical Editorial Illustration: https://www.americanartarchives.com/phillips,c.htm
- Lizzie Harper Editorial Wildlife Illustration: https://lizzieharper.co.uk/project/bbc-wildlife-magazine/
- Bird Magazine with Illustrations Example: https://www.aba.org/magazine/
- Marc Aspinall Illustrator: http://www.thetreehousepress.co.uk