Hinduism has Rishi Marici, who is one of the Saptarshis. Wikipedia says that he is the founder of Vedanta. However the first systematized book on Vedanta is the Brahma Sutras, composed by Badarayana. And the pre-Brahma-Sutra Vedantic authors which we find are Ashmarathya, Badari, Audulomi, Kashakrtsna, Karsnajini and Atreya, as quoted by Badarayana himself.
Jainism poses that Marici was one of the previous births of Vardhamana Mahavira.
Is it by any chance that these two characters are in fact one?
Because there are many overlapping theories, which may or may not be true. They also say that Guru Nanak is a later incarnation of King Janaka.