Monclair was a Colonial painter. One of his original paintings, a depiction of the Cylon War, adorns William Adama's office on the battlestar Galactica (Bastille Day).
Closeup of Monclair's painting of the Cylon War, inset with placement in Adama's quarters
Note
According to Battlestar Galactica: The Official Companion, the painting hanging in Adama's quarters was actually made by additional art director Ken Rabehl.