My favorite genre of self-portrait is cartoonists being bothered by their characters while trying to draw

Bill Watterson – Calvin and Hobbes (1986)

Hergé – Tintin (1947, Tintin Magazine)

Albert Uderzo – Asterix (the cover of Uderzo l'Irreductible (2018), but originally much older)

Jeff Smith – Bone (1993, Bone Holiday Special)

Walt Kelly – Pogo (1950, Maclean's Magazine)

And a bonus:

Berkeley Breathed – Bloom County