Decalon was a male Romulan who defected from the Romulan Star Empire. With the help of another Romulan named Phajan, he made use of the short lived "underground railroad" which ferried defectors into Federation space. For a time he lived on Santora Prime, but in 2380 returned to his former home of Kevratas to aid the Federation in attempting to cure a local plague. He was shot dead by Sela's centurions while saving the life of Beverly Crusher. (TNG novel: Death in Winter)