Freeman is a great teacher as well as a great photographer. Although I haven't attended any of his workshops, I have read all of his books and found them instructive and inspiring.
Tony is a good friend as well as a mentor. He's been inspired by Freeman Patterson, too. In addition to being a great photographer, Tony's books are excellent.
André is Freeman's protégé and has written an excellent book on creative photography called "Dreamscapes".
Katrin is one of the best teachers of digital photography writing today. Her books are not intended for beginners; but if you're beyond beginning in Photoshop, you'll learn a lot from any of her books.
Alain is a classically trained painter who is now one of the best landscape photographers and instructors. His essays are excellent reading. He's published them on his web site and on the Luminous Landscape.com. He also has several excellent podcasts on iTunes. Just search on his name at Luminous Landscape and iTunes.
Cathy and Gordon are my friends and mentors run Adventure Photography. Their photo tours are well-planned and go to great areas for photography. They're always available during a tour for critiquing your composition. Also, they always know where the nearest Denny's restaurant is located for breakfast.
John Paul is one of the most creative people working in digital photography now.
Russ is a retired schoolteacher who lives in the Denver area and is a member of Focus Camera Club, where I'm also a member. Russ leads several Photo tours each year, has published articles in nationally distributed magazines and has a book of his own. Russ and I have led workshops together.
Jim has a wonderfully creative vision. He's currently travelling the East Coast on a 39 ft. catamaran with one human friend and two canine ones.