Thus far, Rumple's been directly connected to 4 other characters' backstories: Cinderella; Belle; Hook; and Regina. When you're dealing with a series that has, to date, featured 11 main characters and a host of major recurring characters, that is a mere 'drop in the bucket'.
I can't remember. Was he connected to Jiminy Cricket, too?
It was also revealed that he taught Cora magic, and they clearly have a history that has yet to be spelled out.