Casio G-Shock GA100 - Bradley James - Damien
It is most likely the black GA100-1A1, but it could be a variation with slightly different colors like the GA100MB-1A or GA100L-1A, both with different dark green accents.
This X-Large G-Shock Ana-Digi, “three-eyed” monster measures 55 x 51.2 x 16.9mm. Large anti-skid buttons provide easy operation, embossed indexes gives a 3-D look and a rivet bezel design adds strength to its overall appearance. The watch is Shock Resistant, 200M Water Resistant, has an Anti-Magnetic Structure and 1/1000th Second Stopwatch with Speed Indicator.
In the same tv series, Omid Abtahi (who plays Amani Golkar, Damien's best friend) wears a Kenneth Cole Reaction KC1405 watch.
A Casio G-Shock GA100 is also worn in season 4 of the series Homeland.