[4] Lefebvre is chiefly important as an excellent and sympathetic teacher who numbered many Americans among his 1500 or more pupils.

Among his famous students were Fernand Khnopff, Kenyon Cox,[3] Félix Vallotton, Ernst Friedrich von Liphart,[5] Georges Rochegrosse,[6] the Scottish-born landscape painter William Hart, Walter Lofthouse Dean, and Edmund C. Tarbell, who became an American Impressionist painter.

[7] Another pupil was the miniaturist Alice Beckington[8] as was Laura Leroux-Revault, the daughter of his friend Louis Hector Leroux.

[9] Jules Benoit-Lévy entered his workshop at the École nationale supérieure des Beaux-Arts.

[10] Lefebvre died in Paris on 24 February 1911 and was buried in the Montmartre Cemetery with a bas-relief depiction of his painting La Vérité on his grave.