Arnold II of Isenburg (c. 1190–1259) was Archbishop of Trier from 1242 to his death. A long-time member of the cathedral chapter in Trier, he held several provostships before being elected as archbishop, succeeding his uncle Theoderich von Wied. The election was controversial, and king Conrad IV of Germany granted the regalia to Rudolf de Ponte, the opposing candidate, instead. A short military conflict ensued, and the dispute ended after Rudolf's death when Arnold was confirmed as archbishop by Pope Innocent IV and consecrated in 1245.
Arnold opposed Conrad and the Hohenstaufen claim to the throne, and elected Henry Raspe and later William II of Holland as German anti-kings. During his reign, he fortified several towns and built various castles. He died in Montabaur in early November 1259 and is buried in Trier Cathedral.