This extensive survey explores the burgeoning field of intelligent agents powered by large language models, examining their design through a brain-inspired modular architecture. The authors systematically investigate core agent components, mechanisms for self-enhancement and adaptation, and the dynamics of collaborative multi-agent systems. A significant portion of the work addresses the crucial aspects of building safe, secure, and beneficial AI agents, outlining potential threats and mitigation strategies. Ultimately, the survey synthesizes interdisciplinary insights to highlight key challenges and opportunities in the ongoing development of these advanced artificial intelligence systems