The Incredibly Sad Princess (Czech title: Šíleně smutná princezna) is a 1968 Czechoslovak film starring Helena Vondráčková and Václav Neckář.

It was televised in the United Kingdom by the BBC as The Madly Sad Princess with Gary Watson voicing a narration over the original Czech dialogue; like many such series it was brought in by Peggy Miller.

His father, the king, promised to marry him off to Princess Helena as part of a peace agreement with the neighbouring kingdom.

So Prince Václav, on the pretext of going to the bathroom, escapes from the royal carriage and rides a borrowed cow to see the princess on his own.

In order to cancel her expected engagement to a prince she does not yet know, she feigns sadness and declares that she will only marry a man who makes her laugh.