Zayed bin Khalifa Al Nahyan
Al Ain Palace Museum
Zayed bin Khalifa was the grandfather of Sheikh Zayed. He was born around 1840 and ruled the Emirate of Abu Dhabi.
This painting of him hangs in the Al Ain Palace Museum along with many other portraits from Sheikh Zayed's family. (It helps to be able to read Arabic for these, since all the names are only written in Arabic.)