Johan Samuel Ahlgren (1764–1816) was a Swedish actor. He belonged to the first pioneer troupe of the Royal Dramatic Theatre.
Ahlgren worked as a clerk when he was employed by Fredric Ristell in the Swedish theatre in Bollhuset in 1787. He was described as a beauty with a pure and clear voice, was recommended for his clear pronunciation and for his posture and played both hero and villain, though he was criticised for overacting because of his hot temperament; because of his good looks, he was often given the parts of lover.
His most acclaimed part was Axel Oxenstierna in Drottning Kristina by Gustav III (1790). Among his other parts was Soliman in Soliman II eller de tre sultaninnorna by Kraus in the 1789–90 season, Appius in Virginia by Paykull and Johan Gyllenstjerna in Siri Brahe och Johan Gyllenstierna by Gustav III the 1790–91 season.
When the theatre of Ristell went bankrupt in 1788, the Royal Dramatic Theatre was founded, which was to be ruled by a board of directors made by the actors themselves under the supervision of the Swedish Academy of Arts. The first supervisor from the academy was the nobleman Gustav Mauritz Armfelt, and the cooperation between him and the actors was stormy; Armfelt felt a great contempt for the acting profession, often made use of disciplinarian punishments and lacked patience for the conflict which often affected the board meetings, and Ahlgren and Abraham de Broen were the actors who were often in conflict with Armfelt; Armfelt wrote to a friend; " It is only with the utmost severity I am able to govern this rabble, and as soon as they tried to defy me, I beat de Broen at the stage with a cane and slapt Ahlgren, and I was so determined to continue with this way of rule, that I would have cut of their ears, if any of these gentlemen dare talk to me about rights." To the king, however, Armfelt reported his great success in his rule over the theatre. King Gustav III of Sweden was aware of the common contempt of the profession of acting, and therefore often gave the actors formal titles to rise their status; Samuel Ahlgren was given the title royal quarter master of the court. Armfelt was quickly replaced as the representative from the Academy and "director" of the theatre, but the conflicts between the director and the actors continued, represented by Ahlgren and de Broen. In 1794, Ahlgren challenged the Academys representative, a nobleman, to a duel and was taken to the regent, Duke Charles, who wanted to but him in jail. Ahlgren was fired from the Royal Dramatic Theatre, it did not help that he and then his wife kneeled to the regent. He was then employed at the Stenborg theatre, where he was enthusiastically welcomed- many actors from the Royal Dramatic Theatre left for the Stenborg Theatre during periods of conflicts with the management, such as Marie Louise Marcadet also did in 1795. Samuel Ahlgren returned to the Royal Dramatic Theatre in 1796.