Sheikh Khalifa bin Zayed bin Sultan Al Nahyan (Arabic:  خليفة بن زايد بن سلطان آل نهيان‎; 7 September 1948 – 13 May 2022) was the second president of the United Arab Emirates and the ruler of Abu Dhabi, serving from November 2004 until his death in May 2022.

Khalifa was the eldest son of Zayed bin Sultan Al Nahyan, the first president of the United Arab Emirates. As crown prince of Abu Dhabi, Khalifa carried out some aspects of the presidency in a de facto capacity from the late 1990s when his father experienced health problems. He succeeded his father as the ruler of Abu Dhabi on 2 November 2004, and the Federal Supreme Council elected him as president of the UAE the following day. As ruler of Abu Dhabi, he attracted cultural and academic centres to Abu Dhabi, helping establish the Louvre Abu Dhabi, New York University Abu Dhabi and Sorbonne University Abu Dhabi. He also established Etihad Airways.

During Khalifa's presidency, the United Arab Emirates became a regional economic powerhouse and its non-oil economy grew. Khalifa was viewed as a pro-Western modernizer whose low-key approach helped steer the country through a tense era in regional politics and forged closer ties with the United States and Israel. As president during the financial crisis of 2007–2008, he directed the payment of billions of dollars in emergency bailout funds into Dubai. On 4 January 2010, the world's tallest man-made structure, originally known as Burj Dubai, was renamed the Burj Khalifa in his honor.

In January 2014, Khalifa had a stroke and was in stable condition after surgery. He then assumed a lower profile in state affairs but retained ceremonial presidential powers. His half-brother Mohamed bin Zayed Al Nahyan carried out public affairs of the state and day-to-day decision-making of the Emirate of Abu Dhabi. In 2018, Forbes named Khalifa in its list of the world's most powerful people. Following his death on May 13 2022, Khalifa was succeeded by his brother Mohamed.