Qin dynasty
Note: King Zhaoxiang of Qin (秦昭襄王) had already been ruling Qin for 51 years when Qin annihilated the Zhou dynasty; however the other six warring states were still independent regimes. Some Chinese historiographers thus used the next year (the 52nd year of King Zhaoxiang of Qin) as the official succession from the Zhou dynasty.
Warring States period
In 221 BC, Qin conquered Qi. 
Qi was the final unconquered warring state. It had not previously contributed or helped other states when Qin was conquering them. As soon as Qin's intention to invade it became clear, Qi swiftly surrendered all its cities, completing the unification of China and ushering in the Qin dynasty. The last Qi king lived out his days in exile in Gong and was not given a posthumous name after death, therefore he is known to posterity by his personal name Jian.