The inter-dimensional entity is an organism that lives in-between different dimensions. When Moya got caught in an inter-dimensional space after trying to Starburst without being fully prepared, this entity was designated to repair the dimensional breach and destroy any extra-dimensional material. The crew of Moya initially believed the entity to be hostile -- however, they eventually perceived its attempts to communicate. John Crichton entered a dimensional rift and spoke with the entity -- learning from the entity how to extract Moya from the interdimensional space.
This is the only recorded encounter with this type of being.
The inter-dimensional entity is derived from Farscape.