This special issue spans planetary geomorphology across the solar system, with a particular focus on comparative planetology and terrestrial analogue studies. This special issue is intended to be of interest for Earth and planetary science communities alike and aims to highlight the valuable insights to be gained from exploring geomorphic processes on multiple planetary bodies. The focus of individual papers in the special issue is flexible. As an example, a paper might focus on a given geomorphic theme (e.g. aeolian fluvial processes, volcanism, impact cratering, glaciation) and explore this topic on another planetary body or planetary bodies with comparisons to analogous processes on Earth (observed remotely, in the field, or in the laboratory). Another approach could be a comparative study of a geomorphic process between two or more planetary bodies other than Earth. Authors are encouraged to reach out to colleagues working on different planetary bodies to achieve this.