Ralph Phillips Lowe (November 27, 1805 – December 22, 1883) was an American judge and the 4th Governor of Iowa.

He settled in the town of Muscatine, and was selected as a representative to the Iowa state constitutional convention in 1844.

He moved to Lee County at the end of the 1840s, and became the district judge succeeding George Henry Williams.

In 1857 he was nominated as the Republican candidate for Governor of Iowa, with Oran Faville as his lieutenant.

He won the election by a narrow margin (38,498 votes to 36,088) and served as governor for two years between 1858 and 1860.