Okay, well I am very much so obsessed with Fullmetal Alchemist and FMA: Brotherhood, so here are some interesting tie-ins from FMA & FMAB to Lux Pain. 
I'm pretty sure you know who is from which anime/game, so I'm not going to specify. xD 

Eric Vale
Solf J. Kimblee 
Hibiki Kiryu 

Monica Rial
Dante 
May Chang 
Natsuki Venefskuja 
Yayoi Kamishiro

Christopher R. Sabat
Alex Louis Armstrong 
Liu Yee    --- SQUEE ---

Colleen Clinkenbeard
Riza Hawkeye 
Rose Thomas
Yui Yamase 

Todd Haberkorn
Ling Yao 
Ryo Unami 

J. Michael Tatum
Scar
Ray Platiere 
Arthur Mays

Japanese Counterparts 

Yuichi Nakamura
Greed 
Akira Mido

Kaori Nazuka
Denny Brosh 
Maria Ross 

Again, the rules are incredibly simple: try not to be too profane and BE POLITE TO OTHER MEMBERS.