Dear all, We are pleased to announce the CoBrain Satellite: Complexity in the Brain, which will be held at the Conference on Complex Systems 2025 (CCS 2025) on September 3rd, 2025, in Siena, Italy. The CoBrain satellite aims to bring together researchers from neuroscience, complex systems, and related fields to explore complexity in brain dynamics, structure, and function. This one-day event's topics include: complex network models of brain connectivity, information theory applied to neural systems, emergent dynamics in neural populations, multi-scale approaches to brain complexity, computational neuroscience, and complex systems. *Confirmed keynote speakers:* Petra Vertes – University of Cambridge, UK. Michele Nardin – HHMI Janelia Research Campus, USA. Giulio Pergola – University of Bari Aldo Moro, Italy. Jaroslav Hlinka – Czech Academy of Sciences, Czech Republic. We are now accepting *abstract submissions for contributed talks <https://kgatica.github.io/CCS2025-CoBrain/#call-section>*. Submissions from underrepresented groups are especially encouraged. Please also ensure you register for CCS 2025 to attend the workshop. For more information and updates, visit our website <https://kgatica.github.io/CCS2025-CoBrain/>. We hope you will join us there! *Organising Committee* Nicola Pedreschi – University of Bari (Chair) Samy Castro – University of Strasbourg (Chair) Jesseba Fernando – Northeastern University Boston (Chair) Marilyn Gatica – Northeastern University London (Chair)