A character is unable to be seen by other characters, but still have a tangible presence and usually can still communicate and/or interact with them. Magic, technology, or the paranormal may be involved. Note that this tag applies even if the viewer can still see them, since the artist would want to let the viewer know that the invisible character(s) is/are still there.

Not to be confused with unseen_character, which is for characters that are "out of frame" to the viewer but are still visible to the characters that can be seen in the post.