Liquid crystals have been extensively used in various applications, such as optoelectronic devices, biomedical applications, sensors and biosensors, and packaging, among others. Liquid crystal polymers are one type of liquid crystal material, combining their intrinsic properties with polymeric flexibility for advanced applications in displays and smart materials. For instance, liquid crystal polymers can serve as drug nanocarriers, forming cubic or hexagonal mesophases, which can be tailored for controlled drug release. Further applications of liquid crystals and liquid crystal polymers include the preparation of membranes for separation processes, such as wastewater treatment. Furthermore, these materials can be used as ion-conducting membranes for fuel cells or lithium batteries due to their broad types of mesophases. This review aims to provide an overall explanation and classification of liquid crystals and liquid crystal polymers. Furthermore, the great potential of these materials relies on their broad range of applications, which are determined by their unique properties. Moreover, this study provides the latest advances in liquid crystal polymer-based membranes and their applications, focusing especially on fuel cells. Moreover, future directions in the applications of various liquid crystals are highlighted.