Giuseppi Verdi mainly wrote operas, but he did write just one string quartet.
"Verdi's production of Aida in early March, 1873 was delayed due to the sudden illness of soprano Teresa Stolz.[1] Verdi focused his time in Naples on the writing of his first chamber work, the String Quartet in E minor. The work was premiered two days after the opening of Aida during an informal recital at his hotel on April 1, 1873.[1] The names of the original performers survive only as Pinto brothers, violins, Salvadore, viola, and Giarritiello, cello. Verdi commented on the work, saying "I've written a Quartet in my leisure moments in Naples. I had it performed one evening in my house, without attaching the least importance to it and without inviting anyone in particular. Only the seven or eight persons who usually come to visit me were present. I don't know whether the Quartet is beautiful or ugly, but I do know that it's a Quartet!" Link
I'm a string quartet addict (2 violins, a viola, and a cello) and this is one of my favorites. Here's the second movement: