Masum bey Qayibov or Nikolai Dmitrievich Qayibov (Azerbaijani: معصوم بگ میرزا محمدقلی بگ اوغلی غائبوف, Məsum bəy Mirzə Məmmədqulu bəy oğlu Qayıbov; b. April 19, 1864, Shusha, Russian Empire - October 20, 1915, Tiflis, Russian Empire) was an Azerbaijani military officer, major general and member of aristocratic Qayibov family.

He entered the service as a private cadet on September 1, 1881 at the 2nd Konstantinovsky Military School.

From October 11, 1891 to April 28, 1893, Lieutenant Mirza Masum bey Qayibov was assigned an official to the headquarter of the Caucasian Military District.

From April 28, 1893 to May 19, 1899, Qayibov served as a junior assistant to the head of the Gorsky branch of the district headquarters.

On February 26, 1904, he was promoted to lieutenant colonel with approval as a senior adjutant of the headquarters of the Caucasian Military District.