Lao Tzu
The author of Tao Te Ching (Tao 道 - Te 徳 / 得 - Ching / King 経 in Chinese Characters / Kanji).
As the title of the book, 道徳経 is commonly used. The second character 徳 means "moral". In old Chinese, a phonetically similar character sometimes substitute the original one. Therefore, in the text, often the character 徳 is interpreted as 得, which means "to attain". 道得(徳) = the attainment of Tao.
Also called Laosi, Lao Tse, Laotze, Lao Zi, Laocius, and other variations.
Lao Tzu, supposedly, lived in 6th century B.C.
He is probably a fictitious character, or the name may have given to collective wisdom of the Taoists at that time.
Lao Tzu, 老子 in Chinese Characters / Kanji, means "an old man" (Lao 老 old. Tzu 子 person in a respectful way). In Japanese, it is pronounced [ro shi] and written ろうし in hiragana / ロウシ in katakana.