Lewis Wellington Hillyer (1818–1897) was an American politician.
Hillyer was a native of Licking County, Ohio, born in 1818.
After attending Granville College, he worked alongside his brother and brother-in-law as a merchant, then joined the wholesaler firm Avery, Butler & Cecil.
Hillyer moved to Taylor County, Iowa, in 1858, and became a farmer.
Politically, Hillyer was affiliated with the Republican Party and served as a county supervisor before his election to the Iowa Senate.