Also fungi. I was curious myself and did some searching. Some non-autotrophic plants include the parasitic Cuscuta and Balanophora. There's also semi-parasites like Loranthus and Santalum (sandlewood). See Wikipedia under "Parasitic_plant". The most relevant term is "holoparasitism" and one page says: Holoparasitism has evolved at least six times independently.
This can't be true: Not all plants are autotrophic, and not all autotrophic organisms are plants.