William (Bill) Adama is the commander of the Galactica in BSG. He is also referred to as "The Old Man".
William Adama was born on Caprica. He was a talented Viper pilot and fought in the First Cylon War. After the war, though, he was discharged from the Colonial Fleet. He married a woman named Carolanne and fathered two sons: Zak and Lee. Using his wife's family's military connections, Adama managed to get both himself and his friend Saul Tigh back in the Fleet. In the end, Adama and Carolanne divorced and he was transferred from the Valkyrie to the Galactica. The Galactica was about to be decomissioned the day the Cylons attacked. After the attack wiped out most of humanity, Adama, as commander of the battleship, is thrust into a leading position alongside with Secretary of Eduaction Laura Roslin.
Personality and Physical Characteristics
William Adama has dark hair, bordering on gray, and blue eyes. He is rather stout and most definetly old. There is a long vertical scar on his chest that was the result from him being shot in the chest by a Cylon.
Personality in Canon
He is devoted to his crew, though sometimes he has an odd way of showing it. He considers the crew of the Galactica to be his family, and thus is viewed as a father figure.
Personality in Badfic
In one particular Badfic which shall remain unnamed, Adama is a creepy psycho vampire stalker who thinks that Laura Roslin is his property. He is also known to father Mary Sues.