Since you did not specify only rock guitarists for your list, let's add some other guys who should be on your list:
Blues guitarists:
1. A: Luther Allison
2. C: Albert Collins; Robert Cray; Johnny Copeland
3. G: Buddy Guy
4. K: B.B. King; Albert King
5. M: Coco Montoya
6. V: Stevie Ray Vaughn
7. S: Son Seals
8. W: Muddy Waters; Johnny Winter
Jazz Guitarists:
1. A: John Abercrombie
1. B: Charlie Byrd; Kenny Burrell
2. C: Charlie Christian; Larry Coryell
3. E: Herb Ellis; Mark Elf
4. F: Tal Farlow; Bill Frisell
5. G: Grant Green
6. H: Jim Hall
7. K: Barney Kessel
8. M: Wes Montgomery; Pat Metheny; Pat Martino
9. P: Joe Pass
10. R: Jimmy Raney; Django Reinhardt; Emily Remler; Lee Ritenour
11. S: John Scofield
12. T: Martin Taylor
Country/rock/miscellaneous:
1. A: Chet Atkins
2. K: Mark Knopfler
Blues guitarists:
1. A: Luther Allison
2. C: Albert Collins; Robert Cray; Johnny Copeland
3. G: Buddy Guy
4. K: B.B. King; Albert King
5. M: Coco Montoya
6. V: Stevie Ray Vaughn
7. S: Son Seals
8. W: Muddy Waters; Johnny Winter
Jazz Guitarists:
1. A: John Abercrombie
1. B: Charlie Byrd; Kenny Burrell
2. C: Charlie Christian; Larry Coryell
3. E: Herb Ellis; Mark Elf
4. F: Tal Farlow; Bill Frisell
5. G: Grant Green
6. H: Jim Hall
7. K: Barney Kessel
8. M: Wes Montgomery; Pat Metheny; Pat Martino
9. P: Joe Pass
10. R: Jimmy Raney; Django Reinhardt; Emily Remler; Lee Ritenour
11. S: John Scofield
12. T: Martin Taylor
Country/rock/miscellaneous:
1. A: Chet Atkins
2. K: Mark Knopfler