Johann Peter Alexander Wagner was a German rococo sculptor.
He was born in Obertheres, Unterfranken, Bavaria, Germany and was initially trained by his father, Johann Thomas Wagner. He moved to Vienna in 1747 and worked under several commissioners including another Johann Wagner and Balthasar Ferdinand Moll; after which he moved to Mannheim and worked under Paul Egell or Augustin Egell. He entered under the court sculptor Johann Wolfgang von der Auwera to Prince–Bishop of Würzburg around 1756 who died that year—Wagner then took his master's widow as his bride, she was named Maria Cordula Curé. He also assumed the workshop of his master along with a brother-in-law, Lukas von der Auwera.
He created several utilitant items over the next several years including a console table, the altar to the Augustinerkirche, Würzburg, the altar and baptismal font to the Stadtpfarrkirche of St Maria and St Regiswindis, Gerolzhofen, Schweinfurt. He collaborated with Lukas von der Auwera between 1763 and 1766 on the Vierröhren Fountain, Würzburg carving the figures. In 1766 he moved on to a purely aesthetic work depicting the Crucifixion for a church in Kürnach.