The most frequent surnames in Catalonia remain Garcia, Martínez, López, Rodríguez, and Sánchez. All five share the characteristic of being composed of between five and nine letters, a trait common to the 25 most frequent surnames in the country, according to the latest data registered by Idescat.

However, much longer, though far less common, surnames exist in Catalonia. The longest registered is Torrentgenerós, consisting of fifteen letters, carried by only sixteen people in total (six as a first surname and ten as a second). The vast majority of individuals bearing the surname Torrentgenerós are registered in the Osona region.

Another notable case is Pratsobrerroca, fourteen letters long, carried by only fifty people nationwide (thirty as first and twenty as second). Twenty of these individuals are registered in Osona, the home region of the writer Gil Pratsobrerroca, author of the book El joc del silenci. Also with fourteen letters is Serradesanferm, held by 143 people in total, mainly in Moianès, Osona, and Barcelonès.

Idescat also records several twelve-letter surnames. The most common of these is Puigdomènech, held by over a thousand people, many of whom reside in Osona. Other examples include Torrabadella, distributed between Berguedà and Bages; Bernatallada, concentrated in Gironès; and Rocadenbosch, the least common of this group, with half of its bearers located in Barcelonès.