I know Jeff Bezos is considered the richest known person but there is a lot of hidden wealth in the world.
I've heard the following people may actually be trillionaires:
Putin
Oil Saudis
Rothschild family
There might be many more rich persons in the world other than these but it depends upon whom you call a rich person. For me having only money, dollars, gold or bitcoins does not make a person rich. For me a person is rich if he is healthy, do not have major problems and sufficient source of income to run his life.