30 Anos Clube do Colecionador is a small six-stamp series issued a few months ago commemorating the 30 years of the Portuguese official philatelic magazine, Clube do Colecionador, reproducing covers of said magazine with a variety of subjects. There are only two reproducing drawings by cartoonists, but it's nice to see these chosen as the most distinctive covers.
That's the one with an old guy complementing a younger one, reproducing a cartoon by Raphael Bordallo Pinheiro, aka Rafael Bordalo Pinheiro (portrayed twice in the cartoon asking for light to his younger self), a very famous cartoonist whom we consider to be the creator of Portuguese comics. The drawing is "just" a cartoon, a very good one, but not from any of his comic strips though. It was originally published in his own magazine A Paródia, on June 11, 1903:
The other, more comics-related stamp in the series reproduces another cover of the postal magazine which actually reproduces the cover of the coffee-table book on the history of Portuguese comics published by the Portuguese Postal Service in 2005, Roteiro Breve da Banda Desenhada em Portugal, written by my friend Carlos Pessoa, which I edited, revised and also supplied many of the illustrations. The drawing of the child, Manecas, lying on a ball is by Stuart Carvalhais from his comic strip series "Quim e Manecas," with some information here: