| Otto I, Count of Scheyern-Dachau-Valley | |
| Noble Family: | House of Wittelsbach |
| Father: | Arnold I, Count of Scheyern |
| Mother: | Beatrix of Reipersberg |
| Spouse: | Adelaide of Weilheim |
| Birth Place: | probably: Dachau |
| Death Date: | after 5 November 1130 |
| Death Place: | probably: Valley |
Otto I, Count of Scheyern-Dachau-Valley (also known as Otto of Dachau-Valley; died after 5 November 1130) was a German nobleman. He was a son of Count Arnold I of Scheyern and his wife, Beatrix of Reipersberg. Otto I was the founder of the Scheyern-Dachau-Valley line.
He acquired the town of Grub via his wife. In 1122, he founded the town of Bernried am Starnberger See and became its vogt. In 1124, he acquired Dachau and the County of Valley (Valley, Bavaria). The branch of the House of Wittelsbach which descended from him, was named after these possessions.
Otto married Adelaide of Weilheim. Together, they had five children: