Among the seven living former prime ministers of Nepal, Khil Raj Regmi(from February 2011 to August 2011) had the shortest term while Lokendra Bahadur Chand has the longest term.
This is a list of the prime ministers and other heads of government of the Kingdom of Nepal and later the Federal Democratic Republic of Nepal. Khil Raj Regmi (2013-March-14) (2014-February-11)March 14, 2013  February 11, 2014
(Acting Prime Minister) Lokendra Bahadur Chand (1983-July-12) (1986-March-21)July 12, 1983  March 21, 1986;
(1990-April-06) (1990-April-19)April 6  April 19, 1990;
(1997-March-12) (1997-October-07)March 12  October 7, 1997;
(2002-October-11) (2003-June-05)October 11, 2002  June 5, 2003 
