His parents were wealthy, so he did not need to endure periods of artistic struggle. Most of his career was spent in Barcelona, though when a young artist he split his time between Barcelona and Paris. He also spent some time in Madrid where he made portrait drawings.
Those drawings were mostly or entirely of men, and men likely were subjects of much of his commissioned portrait work, though images of these paintings are essentially absent in Internet searches. Besides his portrait drawings, most Web images are of women. Some of these are shown below.
Antes del baño - 1894
This is perhaps my favorite Casas painting.
Montserrat Casas - 1888
His older sister.
Belisa Casas amb Vestit Gris - 1889
His younger sister.
En el Moulin de la Galette - 1892
Another well-known painting. Madelaine is smoking a cigar, but that must have been okay in Montmartre in those bohemian days.
La Parisina - 1899
Seven years later, this Parisienne is shown in a costume with similar colors to those seen in the preceding image.
Après le bal - c.1899
Another Paris painting featuring a beautiful young woman.
La Parisienne - 1901
Something of a sketch, but signed and dated by the artist.
Júlia Peraire - c.1908
His model, mistress, and eventual wife.
Lola Vidal de Utrillo (Dolors Vidal Ribot) - 1911
She was the wife of painter Miguel Utrillo, possible father of french painter Maurice Utrillo, son of Suzanne Valadon.
La Trini - 1916