Arjuna totally had 5 wives.
Draupadi
Princess of Panchala kingdom and daughter of Drupada. Together they had a son named Srutakriti.
Ulupi
Arjuna was dragged by Ullupi to the bottom of the sea. Ullupi was the daughter of the king of the Nagas. Ullupi also threatened Arjuna that if he doesn’t accept her then she will commit suicide. They spent one night together and in the next morning, Arjuna left. While leaving, Ullupi granted Arjuna a boon making him invincible in water. They had a son named Iravan. Though they did not marry according to vedic formalities, Arjuna regarded her as his wife. After Ashwamedha sacrifice, Ullupi lived in Hastinapur.
Chitrangada
The King of Manipur,Chitravahana had a beautiful daughter named Chitrangada. Seeing the beauty of Chitrangada, Arjuna asked the king to give his daughter to him. They married and had a son named Babruvahana.
Subadra
Subadra was the beloved sister of Krishna and last wife of Arjuna. Subadra was extremely beautiful and Arjuna desired to posses her. On the advice of Krishna, Arjuna eloped with her. They married in Dwarka. On completion of 12 years exile, Arjuna took her to Indraprasta.
Unnamed sister of Vasuki
After Khandava daha, Arjuna married the sister of Vasuki. Her name is not mentioned in Mahabharata.
Yudhishthira said, "And what office will be performed by that mighty descendant of the Kurus, Dhananjaya, the son of Kunti, that foremost of men possessed of long arms, invincible in fight, and before whom, while he was staying with Krishna, the divine Agni himself desirous of consuming the forest of Khandava had formerly appeared in the guise of a Brahmana? What office will be performed by that best of warriors, Arjuna, who proceeded to that forest and gratified Agni, vanquishing on a single car and slaying huge Nagas and Rakshasas, and who married the sister of Vasuki himself, the king of the Nagas?
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