Spencer is an incorporated hamlet in Clark County, Idaho, United States.

According to the United States Census Bureau, the city has a total area of 1.12 square miles (2.90 km2), all of it land.

38.9% of all households were made up of individuals, and 16.7% had someone living alone who was 65 years of age or older.

The racial makeup of the city was 94.74% White, 2.63% Native American, 2.63% from other races.

17.6% of all households were made up of individuals, and 5.9% had someone living alone who was 65 years of age or older.

There were 40.0% of families and 56.8% of the population living below the poverty line, including 100.0% of under eighteens and none of those over 64.