List all terms under a parent I want to create a taxonomy view, which only displays terms that belong to a certain parent.

However, the "Term ID with depth" filter that appears in a normal view seems to be missing in the Term View type. 

Any ideas how I might go about achieveing this?
just add a relationship for "Taxonomy term: Parent term" and select "require this relationship".
Then add a contextual filter for termID, select "parent" as the relationship and select a fixed value of the parentID.

You can also do it without using relationships. Just add a contextual filter for "Taxonomy term: Parent term" and provide a fixed value for the parent term.