Which characters are featured in the Fullmetal Alchemist: Brotherhood eyecatches? In every episode in the Fullmetal Alchemist: Brotherhood series, about halfway through the episode there is an interruption in which two images (eyecatches) with characters are displayed.  

Which characters are featured and how many times?
I will refer to the first eyecatch of each episode by the number of that episode suffixed by the letter a, and to the second by appending the suffix b.
I have considered the names displayed along the images for this count. Thus, some characters may appear more than once referred to by different names, like King Bradley and Wrath (since these may be regarded as alter-egos), and some may only have reference to the fact that the name appear shortened or something similar, like Winry and Winry Rockbell. The only debatable choice is that I differentiated between Greed in his first body and in Ling Yao's body. But then again, you just need to add one to your count if you'd rather count them as only one character (since Greed only appears once in his first body).
The list follows the order of first appearance, appending the number of the episode a character may have been re-featured after the name.  


Edward Elric - 1a, 2b (as Edward Elric 11 years old), 20b, 26a, 35a, 41b, 44b, 45b, 63a, 64a (as Edward)  
Alphonse Elric - 1b, 2a (as Alphonse Elric 10 years old), 20a, 26b, 35b, 51b, 64a (as Alphonse)  
Cornello - 3a  
Rose - 3b  
Nina - 4a  
Alexander - 4a  
Shou Tucker - 4b  
Roy Mustang - 5a, 10b, 17b, 29a, 31a, 53b, 62a (as Mustang)  
Scar - 5b, 21b, 22b, 59b, 61b  
Tim Marcoh - 6a, 29b, 43a  
Winry Rockbell - 6b, 9b, 22a (as Winry), 23b (as Winry), 39a, 44a, 46a, 60b, 64a (as Winry)  
Sheska - 7a  
Maria Ross - 7b, 18b, 50a  
Denny Brosh - 7b  
Slicer - 8a  
Barry The Chopper - 8b  
Hughes Family - 9a  
Maes Hughes - 10a  
Paninya - 11a  
Dominic - 11b  
Sig Curtis - 12a, 12b (without name)  
Izumi Curtis - 12a, 12b (without name)  
Roa - 13a, 14a  
Bido - 13a  
Martel - 13a, 14b  
Dolcetto - 13a, 14a  
Greed (first) - 13b  
May Chang - 15a, 25a, 60a  
Shao May - 15a, 25a, 60a  
Ling Yao - 15b, 28a  
Focker - 16a  
Gracia Hughes - 16b  
Henry Douglas - 17a  
Alex Louis Armstrong - 18a, 43b (as Alex), 45a (as Alex), 52b, 55a (as Alex)  
Jean Havoc - 19a, 21a, 50a  
Lust - 19b, 25b  
Lan Fan - 23a, 24a, 48a  
Envy - 24b, 53a, 54a  
Van Hohenheim - 27a, 42b, 50b (as Hohenheim), 63b  
Pinako Rockbell - 27b  
Greed (Lin Yao) - 28b, 45a, 47a, 56b  
Riza Hawkeye - 30a, 30b, 58b, 59a (as Hawkeye), 62a (as Hawkeye)  
Solf J. Kimbley - 31b, 33a, 41a, 49b (as Kimblee)  
Grumman - 32a (as Mrs.(?) Grumman), 47b  
Selim Bradley - 32b, 37a  
Olivier Mira Armstrong - 33b, 36b, 43b (as Olivier), 45a (as Olivier), 55a (as Olivier)  
Miles - 34a  
Sloth - 34b, 54b  
Raven - 36a  
Pride - 37b, 42a, 49a  
Yoki - 38a  
Zampano - 38b, 39b  
Jerso - 38b, 39b  
Slave Number 23 - 40a  
The Little One Inside the Flask - 40b  
Wrath - 45a  
King Bradley - 46b, 56a, 61a  
Gluttony - 48b  
Mannequin Soldiers - 51a  
Heinkel - 52a  
Karley - 55b  
Fu - 57a  
Gold-Toothed Doctor - 57b  
Buccaneer - 58a  
Darius - 59a  
Scar's Brother - 61b  
Our Father - 62b  
Trisha Elric - 63b  
Roy's Team - 64b  


The number of times each character that is featured more than once appears, in decreasing order:
Edward Elric is featured 10 times, Winry Rockbell 9 times, Alphonse Elric 7 times, Roy Mustang 7 times, Scar 5 times, Alex Louis Armstrong 5 times, Olivier Mira Armstrong 5 times, Van Hohenheim 4 times, Greed (in Lin Yao's body) 4 times, Riza Hawkeye 4 times, Solf J. Kimbley 4 times, Tim Marcoh 3 times, Maria Ross 3 times, May Chang 3 times, Shao May 3 times, Jean Havoc 3 times, Lan Fan 3 times, Envy 3 times, Pride 3 times, King Bradley 3 times, Sig Curtis 2 times, Izumi Curtis 2 times, Roa 2 times, Martel 2 times, Dolcetto 2 times, Ling Yao 2 times, Lust 2 times, Grumman 2 times, Selim Bradley 2 times, Sloth 2 times, Zampano 2 times, Jerso 2 times, and every other featured character appears only once.

This count may differ if one decided to count the number of times a character is seen, since some characters appear without being referenced by their name, like in the case of Roy's Team in the last eyecatch. If one decides to count those, one should add: 2 to the count of Maes Hughes (9a as Hughes Family, 10b back facing camera), 1 to Gracia Hughes (9a as Hughes Family), 1 to Elicia Hughes (9a as Hughes Family), 2 to Roy Mustang (10a back facing camera, 64b as Roy's Team), 1 to Envy (16a shadow can be seen behind Focker), 1 to Riza Hawkeye (64b as Roy's Team), 1 to Jean Havoc (64b as Roy's Team), 1 to Kain Fuery (64b as Roy's Team), 1 to Vato Falman (64b as Roy's Team), 1 to Heymans Breda (64b as Roy's Team) and 1 to Black Hayate (64b as Roy's Team).

All the image files are contained in this Google Drive folder (it contains a full-sized and a thumbnail for each of them, 'cause it's the same folder I used to upload the pics to Taisho).