Short form of names starting with Ran-, such as Randall, Randolph and Ranulph. A known bearer of this name is Sir Ranulph Fiennes (b. 1944), who is called Ran by his family and friends.
From Chinese 冉 (rǎn) meaning "tender, weak", 然 (rán) meaning "so, thus, correct, right" or 染 (rǎn) meaning "dye, tint", as well as other characters that are pronounced similarly.