what is the name of the religious leader of Taoism?

like a rabbi would be for Judaism

I'm not sure, but adepts and immortals come to mind. I don't know if there's a central Taoist authority.

A priest.

Notorious big.

There is none.

Its founder, Lao-Tu

The philosophy was founded by Lao Tzu.
The initiated Taoist priest saw the many gods as manifestations of the one Dao. He had been ritually trained to know the names, ranks, and powers of important spirits, and to ritually direct them through meditation and visualization. In his meditations, he harmonized and reunited them into their unity with the one Dao. However, only the educated believers knew anything of the complex theological system of the priest.

They do have monks and priests and this order is known as the Way of Complete Perfection, and another organization is called the Way of the Heavenly Masters and traces itself back to the 2ND century teacher, Zhang Daoling. It is said that he had visions of Lao Zui. The control of this organization is hereditary through the paternal lineage, and they have parishes set up.