Siddiqui, (also rendered as Siddiqi, Siddique, Siddiquee, Siddighi, Sadighi, Seddighi, Sidiki or Siddiquie) (Arabic: صدیقی‎) is a Muslim family name, found in the South Asia and the Middle East. Shaikh is an additional title used occasionally by Siddiqui/Siddique to signify their Arab heritage. People having surname "Siddiqui" are offspring of Abu Bakr Siddiq (Arabic: ابو بكر الصديق‎), the first Caliph and an early companion and a close friend of the Prophet Muhammad.

The name "Siddiqui" derives from the word Siddiq, which means "truthful" in Arabic. "Al-Siddiq" was the title accorded to Abu Bakr (Arabic: ابو بكر الصديق‎), the first Caliph and friend of the Prophet Muhammad. The surname "Siddiqui/Siddiqi" signifies ancestry from Abu Bakr Siddiq.

Abu Bakr belonged to the Banu Taym clan of the Quraish. The genealogy of Abu Bakr joined that of the Prophet Muhammad in the eighth degree in their common ancestor Murrah ibn Ka'b. Four generations of the family of Abu Bakr Siddiq had the distinction of being the companions (Sahaba) of the Prophet Muhammad namely Abu Bakr, his father Uthman Abu Quhafa, his eldest son Abdu'l-Rahman and his grandson Abu Atiq Muhammad. No other family had this honour. Many Siddiqui families descend from this particular lineage. On the other hand, the Siddiqui families who are the progeny of Muhammad ibn Abi Bakr, the youngest son of Abu Bakr descend from three generations of Sahaba. The lineage of Abu Bakr did not continue through his middle son Abdullah ibn Abi Bakr who was wounded during the Siege of Taif and later died of these wounds.

Chief Justice Saeeduzzaman Siddiqui or Saeed-uz-zaman Siddiqui (Urdu : سعید الزماں صدیقی) (born 1 December 1937) in Lukhnow, British India; is a Pakistani Jurist and legislator who formerly served as the Chief Justice of Pakistan at the Supreme Court of Pakistan. He was the Chief Justice of Pakistan when 1999 military coup d'état was staged by then-Chairman of the Joint Chiefs of Staff Committee and Chief of Army Staff General Pervez Musharraf. He defied the request given by Musharraf via the Law Minister and Legal Adviser Sharifuddin Pirzada to take a new oath under the Provisional Constitutional Order (PCO) saying that "taking oath under the PCO, in my opinion, will be a deviation from the oath I had taken to defend the constitution of 1973".

As a consequence of this he was forced to step down from his position, by General Pervez Musharraf. The tenure time period was shortened due to his refusal to take the Provisional Constitutional Order (PCO) Oath, prescribed by General Pervez Musharraf to legitimize the LFO. After a long discussion with 4 Army generals send to his residence by General Musharraf; namely, Lieutenant-General (Retired) Moinuddin Haider, who was Interior Minister,then-Lieutenant-General Ehsan ul Haq, Core-commander of the XI Corps, Lieutenant-General (retired) Mahmud Ahmed, then-Director General of the ISI and Brigadier-General (retired) Javed Ashraf Bajwa; Chief Justice Siddiqui refused to take the Oath they left and on orders of the GHQ he and his family were placed under house arrest.