Add to ORKGInternational audienceThe H.E.S.S. Imaging Air Cherenkov Telescope system is very well suited to perform follow-up observations of detections at other wavelengths or messengers due to its fast reaction and its comparably low energy threshold. These advantages are fully exploited via a largely automatized system reacting to alerts from various partner observatories covering all wavelengths and astrophysical messengers. In this contribution we provide an overview and recent results from H.E.S.S. programs to follow up on multi-wavelength and multi-messenger alerts. We present ToO observations searching for high-energy gamma-ray emission in coincidence with electromagnetic transients Fast Radio Bursts as well as multi-messenger transients relat...