This article reports on a single layer penta-bandstop frequency selective surface (FSS) for multiband shielding applications. The proposed unit cell incorporates five independent resonant elements that are realized on a single-sided FR4 substrate to suppress GSM - 0.9 GHz, GPS - 1.5 GHz, GSM - 1.8 GHz, Wi-Max - 3.5 GHz, and Wireless Local Area Network (WLAN) - 5.7 GHz frequency bands. The proposed single layer unit cell has compact lattice periodicity of order 0.11 lambda(o) x 0.11 lambda(o). The design is not only polarization-insensitive, but it also offers high angular stability up to 45 degrees. A detailed parametric analysis is conducted to establish a relationship between geometrical parameters and FSS spectral response. Additionally, an equivalent lumped circuit model is also derived to further elaborate on the underlying resonance mechanism. A prototype is fabricated and tested to validate the performance of the proposed FSS. The measured results are in good agreement with simulated ones. The proposed FSS has the uniqueness of suppressing 0.9 GHz GSM band that has never been reported in a pentaband design. The proposed FSS is a potential candidate for radio frequency (RF) shielding, electromagnetic wave suppression, and data security applications in secure installations.