Alexander SIDDIG (or Sid as he is known now) was born in Sudan but has spent most of his life in England.  He was born to an English mother who worked as a theatrical consultant and a Sudanese father.  His maternal uncle is English actor Malcolm McDowell, with whom he appeared in 2008 in Neil Marshall's Doomsday, and his paternal uncle is the former Sudanese Prime Minister Sadiq al-Mahdi.

Sid attended the London Academy of Music and Dramatic Art (LAMDA) to study acting and after leaving LAMDA, he completed a season of stage work in Manchester.  Thereafter, Sid worked as a director in a small theatre in London and first appeared to television audiences as Prince Feisal in A Dangerous Man: Lawrence After Arabia, the 1990 TV sequel to Lawrence of Arabia.

Sid's performance in A Dangerous Man brought him to the attention of Rick Berman who was creating the new series Star Trek: Deep Space Nine (1993).  Originally brought in to audition for the role of Commander Benjamin Sisko, Berman decided Sid was too young for the role and cast him as Dr. Julian Bashir instead.

Since the end of the seven seasons of Star Trek: Deep Space Nine, Sid has made prominent appearances in films and television.  Highlights include appearing as an Algerian secret agent on the trail of Islamists in the controversial episode "Nest of Angels" of the British television show Spooks (known as MI-5 in the US) in 2003.  In 2005, he appeared as Saladin's aide, Imad, in Ridley Scott's film Kingdom of Heaven and also gave a critically lauded performance as Prince Nasir in Syriana, alongside George Clooney and Matt Damon.  In 2006 Sid played the title role in Hannibal – Rome's Worst Nightmare for the BBC.  Early 2007, Sid joined the cast of Un Homme Perdu (aka A Lost Man) and he returned to American television in the role of former terrorist Hamri Al-Assad for the sixth season of 24.  In 2009, he co-starred with Patricia Clarkson in the award-winning film Cairo Time (2009) as Tareq Khalifa, an Egyptian who battles his attraction to his friend's wife.

In 2013, Siddig appeared as a Syrian-Canadian in the IFC film Inescapable with Marisa Tomei and Joshua Jackson, and as King Minos in the BBC show Atlantis.  In 2015 he joined the cast of the HBO series Game of Thrones in season 5 as Doran Martell, the ruling Prince of Dorne.

In Baby Mine Sid plays the role of the Iranian father Soroush.