That was the island country of Nauru which sent one athlete to the 2008 Games. That was weightlifter Itte Detenamo who finished 10th in the super heavyweight class.
Yes at least one country has boycotted every olympics
moroco they sent 6
Bhutan,British Virgin Islands,Dominica, Equatorial Guinea,Gambia, Mauritania, Nauru ,São Tomé and Príncipe ,Sierra Leone, Somalia, and timor all with 2 representatives