This page contains information regarding PIC, and thus may contain spoilers.
The Three Musketeers was an Earth book written by Alexandre Dumas during the planet's 19th century. The novel revolved around the three eponymous musketeers – Athos, Porthos, and Aramis – and an up-and-coming musketeer named D'Artagnan. Other characters included Richelieu and Jussac.
A litter of four puppies born in the 2140s were each named after the four main characters from the novel – the four musketeers (including D'Artagnan, who becomes a musketeer by the end of the novel). One of the puppies, Porthos, was given to Jonathan Archer as a pet. (ENT: "A Night in Sickbay")
In the 2360s, Reginald Barclay created a holoprogram based on the novel aboard the USS Enterprise-D. Barclay had holographic representations of Captain Picard, Data, and Geordi La Forge portraying the three main characters. (TNG: "Hollow Pursuits")
Later, crewmembers such as La Forge actively participated in the program. In 2375, Miles O'Brien and Worf reminisced about the program while O'Brien tried to learn why Worf was upset, with O'Brien recalling "Geordi waving that sword around". (DS9: "Image in the Sand")