Mortimer H. Goddin, Radical Republican politician, was born in Richmond, Virginia, on January 4, 1828. He and his wife, Elvira, a native of South Carolina, lived in Alabama before moving to Polk County, Texas, in 1856. They had two children in Alabama and two more after arriving in Texas. Elvira Goddin brought considerable wealth to the family. The census of 1860 reported that she owned fifty-four slaves and more than $75,000 in real and personal property. M. H. Goddin listed his occupation as "planter" but reported owning no property. During the secession crisis and Civil War, Goddin supported the Union. He remained in Polk County during the war but, in spite of the fact that he was only in his mid-thirties, avoided doing anything to support the Confederacy. Elvira died in late 1865.
Provisional governor Andrew J. Hamilton appointed Goddin to the position of justice of the peace in Polk County in October 1865. Goddin won election to the same office on June 25, 1866, and served until December 1867. In the meantime, on April 1, 1867, he accepted appointment as subassistant commissioner of the Freedmen's Bureau in Polk County. His tenure as a bureau agent had few calm moments. His efforts to aid freedmen and his sneering smugness at the defeat of the Confederacy drew the wrath of White conservatives and led him to fear for his life and threaten to arm Blacks and use them to uphold the law. One Polk County Republican commented that local newspapers made Goddin seem non compos mentis but that in fact he was a "terror of the Rebels in this county." A bureau agent in neighboring Tyler County, however, criticized Goddin's judgment in dealing with Southern Whites and contended that he had such bitter personal feelings that he introduced politics into all relationships. The bureau removed Goddin from his post in September 1867, and soon thereafter he was assaulted by four armed men and "compelled to beg for his life."
In February 1868 Goddin, thanks to newly enfranchised Black voters, won election from Polk County to the Constitutional Convention of 1868–69. He acted there as a supporter of the Radical Republicans led by Edmund J. Davis. While serving in the convention, he moved to Huntsville, where he edited the Huntsville Union Republican and continued to be a center of controversy. He refused to pay a note given William H. Howard, his former partner in the newspaper and the local Freedmen's Bureau agent. When Howard went to court, Goddin urged Blacks to demand that the agent be fired. Once the Constitution of 1869 was completed, Goddin, on appointment from Governor Davis, served briefly as district clerk in early 1870 and became mayor of Huntsville in December of that year.
Goddin won the position of presiding justice of the county court of Walker County in a special election on July 13, 1871, and was reelected at the next general election on December 2, 1873. His last political success came in August 1875, when he won a seat in the constitutional convention elected to rewrite the so-called "Radical" Constitution of 1869. (Several authorities have identified Goddin as a Black member of the convention, perhaps because he had such a dark complexion, but the censuses of 1860 and 1870 and much other evidence clearly show that he was White.) He took the oath of office at the convention in Austin on September 10, 1875, but resigned the next day. He gave no explanation of his resignation, although some conservatives in the convention argued that he was not of sound mind. Goddin returned to Walker County and resigned from his position on the county court on November 11, 1875. The next year he reported owning land in San Jacinto County, but then he disappeared from historical public records in Texas, perhaps by leaving the state or by death before the enumeration of population in the census of 1880.