WHO IS KRISTINA KENEALLY?
* Born in Las Vegas in 1968 to an American father and Australian mother, she grew up primarily in Toledo, Ohio.
* Has a degree in political science and a master's in religious studies from the University of Dayton.
* Met husband, Australian Ben Keneally, in 1991 and emigrated to Australia in 1994, where she was NSW youth coordinator for the Society of St Vincent de Paul for two years.
* Became an Australian citizen and joined the Labor party in 2000. She was elected member for Heffron, in Sydney's east, in 2003 and re-elected in 2007, holding ministerial positions in ageing and disability, planning and infrastructure.
* Ousted premier Nathan Rees 47-21 in a leadership spill in late 2009 becoming the first female premier of NSW.
* Rees said whoever replaced him would be a puppet of right-wing powerbrokers Eddie Obeid and Joe Tripodi, prompting Keneally to memorably declare: "Let me be absolutely clear on this: I am nobody's puppet, I'm nobody's protege, I'm nobody's girl."
* Stood down as leader in 2011 after her government suffered NSW Labor's worst election defeat.
* Quit politics to become chief executive of Basketball Australia, then, in 2014 a Sky News pundit.
* After a 2017 report found Obeid, Tripodi and fellow Labor MP Tony Kelly had engaged in serious corrupt conduct, Ms Keneally said they had "operated in secret".
* Named Labor's candidate for the Bennelong by-election to be held in mid-December.
WHO IS JOHN ALEXANDER?
* Born in Sydney in 1951.
* A tennis champion with a career running from the late 1960s to the mid-1980s Alexander claimed seven singles titles and 27 doubles titles.
* Held tennis roles after retiring from playing as Tennis Australia's chair of player development and coach of the Federation Cup team.
* Has also been managing director of Next Generation Clubs Australia, managing a variety of sport-related small business. He was involved in the construction of the Ryde Aquatic Centre for the Sydney 2000 Olympic Games.
* Reclaimed John Howard's northern Sydney seat of Bennelong for the Liberals at the 2010 election from Labor's Maxine McKew.
* Has shown a particular interest in housing affordability, being among Liberal MPs to have urged the government to rethink its opposition to reining in negative gearing.
* Resigned from parliament on November 11 as he most likely holds British citizenship from his father who came to Australia in 1911, 40 years before Alexander was born.