Andrei Chekov

From Memory Alpha, the free Star Trek reference.

Andrei Chekov was a Human of Russian descent living in the early 23rd century. In 2245, he became a father with the birth of his son Pavel Andreievich. (TOS: "The Way to Eden")

Although Andrei was never mentioned in dialog or scripts, we know his name because Pavel's middle name "Andreievich" is an example of a patronymic.