The ACSys workshop invites submissions exploring the multifaceted domain of agents and complex systems. We welcome contributions that delve into the foundational principles of classic agents and multi-agent systems (MAS), addressing topics such as distributed problem-solving, coordination, and emergent behavior. Recognizing the transformative impact of large language models (LLMs), we also encourage submissions investigating contemporary trends in LLM-based agents, including their application in complex environments, their capacity for advanced reasoning, and their integration within hybrid agent architectures. We aim to foster a dialogue between traditional and cutting-edge approaches, bridging the gap between established MAS paradigms and the exciting possibilities offered by LLMs. We encourage research that demonstrates the practical impact of integrated agent systems across diverse and significant real-world applications like health, manufacturing, energy, transportation, and security, as well as broader domains where these technologies can address complex challenges.