This study realizes integrated polarizer and RGB (red, green, and blue) color filters using single- and multiple-layered subwavelength metallic grating structures. A hybrid numerical scheme based on the rigorous coupled-wave analysis method and a genetic algorithm is used to determine the optimal values of the grating period, filling factor, and grating thickness of three different grating structures, namely, a single-layer grating, a double-layer grating, and a double-layer grating with a lateral shift. The optical performance of the various structures is evaluated and compared in terms of the transmission efficiency at the center wavelengths 700.0 nm, 546.1 nm, and 435.8 nm of red, green, and blue light, respectively, and the extinction ratio over the visible wavelength spectrum (380-780 nm). It is shown that the double-layer grating achieves a transmission efficiency of about 50% and an extinction ratio of around 60 dB. Thus, this grating structure provides a convenient and effective means of achieving the polarizing and filtering functions in LCD panels using a single device.