Dionysius I (Дионисий in Russian; real name: Давид, or David) (1300? - October 15, 1385) was a Russian metropolitan in 1384-1385.

Dionysius is known to have spent his younger years in a cave that he dug out himself on the banks of the Volga River not far from Nizhny Novgorod. Later, Dionysius founded the Pechersky Monastery on that same spot. In 1364, he was appointed Archbishop of Suzdal and won love and respect on the part of the locals. In 1378, Dionysius was recommended for the metropolitan post by Sergii Radonezhsky after the death of metropolitan Alexius. However, Grand Prince Dmitri Donskoi had his own candidate - a priest by the name of Mikhail. This cause severe friction between the two clergymen. If elected, Mikhail wanted to introduce a new way of ordaining metropolitan at home, in Russia. Dionysius was against it and in 1379 decided to go to Constantinople to seek concecration from the patriarch. Mikhail was afraid that Dionysius would get the patriarch's blessing and followed him to Constantinople. However, Mikhail died on his way there and one of his accompanying clergymen, namely archmandrite Pimen , reached Czargrad before Dionysius and was named metropolitan of Russia instead of Mikhail. In 1383, Dionysius returned from his trip to his congregation as an archbishop and set Dmitri Donskoi against Pimen. In 1384, Dionysius was sent to back Constantinople to ask for Pimen's deposition and his appointment as metropolitan. Patriarch Neilus Kerameus was not sure whether he could trust Dionysius and sent two metropolitans to Moscow, who were supposed to depose Pimen and ordain the archbishop of Suzdal. On his way back to Moscow, Dionysius stopped in Kiev, where he was detained by the Kievan prince Vladimir Olgerdovich at the insistence of Cyprian, archbishop of Kiev, who had set his sights on the metropolitan post in Moscow. Dionysius died in detention.

The Russian Orthodox Church used to celebrate his memory on July 19 and October 15, but subsequently this tradition died down.