Question: Who was the third caliph?
Answer: The Umayyad family had first come to power under the third caliph, Uthman ibn Affan (r. 644656), but the Umayyad regime was founded by Muawiya ibn Abi Sufyan, long-time governor of Syria, after the end of the First Muslim Civil War in 661 CE/41 AH.
Is the question answered in a satisfactory fashion?
yes