We present a metamaterial based terahertz (THz) detector. The detector design, which combines metamaterials and MEMs, is frequency selective, and we have fabricated and tested detectors at 95 GHz and 693 GHz with noise equivalent powers of 1.13 x 10-8 W/√Hz and 2.96 x 10-8 W/√Hz and responsivities of 16,500 V/W and 6,800 V/W, respectively. These values were achieved at room temperature and pressure. © 2010 Optical Society of America.