Northern Illinois University (NIU) is a public research university in DeKalb, Illinois, United States. It was founded as "Northern Illinois State Normal School" in 1895 by Illinois Governor John P. Altgeld, initially to provide the state with college-educated teachers. In addition to the main campus in DeKalb, it has satellite centers in Chicago, Naperville, Rockford, and Oregon, Illinois.

The university is composed of seven degree-granting colleges and has a student body of approximately 16,000. NIU is one of seven public universities in Illinois that compete in the National Collegiate Athletic Association's, Division I. The athletic teams are known as the Huskies and compete in the Mid-American Conference (MAC).

Northern Illinois University was founded as part of the expansion of the normal school program established in 1857 in Normal, Illinois. In 1895, the state legislature created a board of trustees for the governance of the Northern Illinois State Normal School, which would grow into what is today known as NIU.

In July 1917, the Illinois Senate consolidated the boards of trustees for the five state normal schools (Eastern Illinois State Normal School, Illinois State Normal School, Northern Illinois State Normal School, Southern Illinois State Normal University, and Western Illinois State Normal School) into one state Normal School Board.

Over the next fifty-eight years, the school and the governing board changed their names several times. In 1921, the legislature gave the institution the name Northern Illinois State Teachers College and empowered it to award the four-year Bachelor of Education degree. In 1941, the Normal School Board changed its name to the Teachers College Board. In 1951 the Teachers College Board authorized the college to grant the degree Master of Science in education, and the institution's Graduate School was established. On July 1, 1955, the state legislature renamed the college Northern Illinois State College and authorized the college to broaden its educational services by offering academic work in areas other than teacher education. The Teachers College Board granted permission for the college to add curricula leading to the degrees Bachelor of Arts and Bachelor of Science. On July 1, 1957, the Seventieth General Assembly renamed Northern Illinois State College as Northern Illinois University in recognition of its expanded status as a liberal arts university.

In 1965, the Illinois State Teachers College Board became the Board of Governors of State Colleges and Universities and was reorganized to include Northeastern University, Governor's State, and Chicago State Universities. In 1967 authority for Northern Illinois University, Illinois State University, and Sangamon State University were passed on to a newly formed board of regents. In 1984, the board created the position of chancellor for the three regent universities to act as a chief executive for all three schools. In 1996, authority for each of the three regency universities was transferred to three independent boards of trustees, each concerned with only one university.

In 2008, the university drew international attention when a gunman opened fire in a crowd of students on campus, killing five students and injuring 17 more people before fatally shooting himself.

Thirteen presidents have served at the university. See above article.