Mortadelo y Filemón - Agencia de información is,
without any doubt, the most important spanish comic. Created by Francisco
Ibáñez's brilliant head (yeah, he's bald :-) ), they
appeared for the very first time in _Pulgarcito_ #1934, in january 20, 1958; in
1969 they began working for the T.I.A..
Very quickly they went up to the same category of another european comics (such as Astérix, Lucky Luke, Tintin, etc.) with the standard hard-cover edition of their adventures. Nowadays they are published in several languages (Spanish, Catalonian, Basque, French, Dutch, German, Swedish, English and Polish, at least).
Another outstanding comics made by Francisco Ibáñez are:
[versión en castellano] - [english version]