It is not appropriate or possible to have a definitive list of entities as structures can be complex and change over time and entities leave and enter the sector.
Nid yw'n briodol nac yn bosibl cael rhestr ddiffiniol o endidau oherwydd gall strwythurau fod yn gymhleth a newid dros amser a gall endidau adael y sector ac ymuno ag ef.