Johan Valckenaer (Franeker, 21 January 1759 - outside Bennebroek, 1821) was a Dutch lawyer, patriot and diplomat.
His father Lodewijk Caspar Valckenaer was Franeker university's professor of law and, in 1766, was appointed to succeed Tiberius Hemsterhuis at Leiden. Johan, in the meantime, had become deeply interested in classical and French writers such as Voltaire and Rousseau. He graduated in 1781. His family was related to the Luzacs, publishers of the internationally renowned newspaper "Gazette de Leyde" - Emilie Luzac and her father Johan were Valckenaer's cousins.
In 1782, Valckenaer was appointed to the College of Franeker, but in May 1787 was discharged for his membership of an exercitiegenootschap. He got an appointment in Utrecht, then a democratic Patriot stronghold. At the beginning September Valckenaer tried in vain to organize a force to hold back Frisian state members under the leadership of Court Lambertus van Beyma, trying to create an alternative Provincial States at Franeker. A few weeks later, after the raid on the Netherlands by a Prussian army, many patriots fled in the first place to Amsterdam, then to Brussels and Saint-Omer in northern France. The most important Patriots, such as Wybo Fijnje, H. W. Daendels, Adam Gerard Mappa and Valckenaer lived temporarily in a castle in Watten and formed a kind of commune, that jointly bought a billiards set, restored the rooms and grew its own vegetables.
In between Valckenaer and Van Beyma were no friends anymore. In his flight from Franeker, Van Beyma forgot to take signed and extremely chargeable documents with him, so that a large group of Frisian patriots could be jailed and within two years condemned. Valckenaer was furious. Then both men also got into a quarrel over the distribution of the travel expenses. Nevertheless, Van Beyma and Valckenaer both organized the benefit payments originating from the French state. A difference of understanding between Valckenaer and Van Beyma about leadership in politics, the establishment of an employment project, a shipbuilding enterprise in Gravelines, the care of the administration and the size of the payments brought about an even more violent break between them, with Valckenaeristen and Beymanisten factions of Patriots fighting each other in pamphlets. The dispute reached a climax in 1791. Valckenaer got no payment from Van Beyma, but did get the support of the patriot members of the former political establishment and so won the dispute. In 1792, the commune was dissolved and a Batavian Revolutionary Committee set up.
In January 1795, the "Batavian Legion over the Rhine" carried out a velvet revolution. Johan Valckenaar got an appointment in Leiden. In 1796, he was chosen as a member of the Batavian Republic's National Assembly. Already freely shortly was he of opinion that the revolutions had come full circle and accepted an embassy from Madrid, and attempted to get the Spanish support against England.
In the Netherlands, he chose to return to being a gentleman farmer (Hereboer), as a hoofdingeland of the Rhine country. In 1805 he also had contact with Maria Hulshoff. Under king Louis Bonaparte, he became a financial counsellor.
He died in 1821 in his mansion outside Bennebroek, where he regularly invited his friends Theodorus van Kooten (who had also traveled with him to Spain), Samuel Iperusz Wiselius, Willem Bilderdijk and Anton Reinhard Falck.