Born in Spokane, Washington, Nellis was raised in northwestern Montana and graduated from Libby High School in 1972, and attended Montana State University in Bozeman. He earned a bachelor's degree in earth sciences/geography in 1976 and attended graduate school at Oregon State University in Corvallis, earning a master's in geography in 1977 and a Ph.D. in geography in 1980. Nellis wrote his doctoral dissertation on remote sensing in water resource management.
After graduate school, Nellis has worked for over 30 years in various progressive administrative roles at Kansas State University, West Virginia University, University of Idaho, and Texas Tech University. At Kansas State, Nellis was a department head, Associate Dean, and after returning from West Virginia (where he served as dean of the Eberly College of Arts and Sciences), served as provost and Senior Vice President from 2004 until his departure for the university presidency at Idaho in 2009. He became president of Texas Tech in June 2013.
Nellis' research has focused on geographic information systems and remote sensing, and he is internationally recognized for his work in this area, including receiving numerous university, national and international teaching, research and advising awards, and serving as president (2002-2003) of the Association of American Geographers, President of the National Council for Geographic Education (1993-1994), and President of Gamma Theta Upsilon, The International Honor Geographical Society (1999-2000).
While at Idaho (2009–2013), Nellis led a major $225 million capital campaign, oversaw over $80 million in campus facility improvements, created the President’s Diversity Council, enhanced what became a nationally award winning engagement effort through creation of the Office for Community Partnerships, improved major inter-disciplinary initiatives, and significantly improved business partnerships between the university and business and commodity groups in Idaho and throughout the northwest.
While president at the University of Idaho, Nellis was a member of the BCS Presidential Oversight Committee.
As a nationally recognized higher education leader, Nellis has served as a commissioner for the Northwest Commission of Colleges and Universities (one of 8 nationally recognized accreditation bodies). He also served as a Governor-appointed commissioner of the Western Interstate Commission for Higher Education, which coordinates higher education efforts for the 15 western states, and has been involved in various national committees for the Association of Public and Land-Grant Universities (APLU). Since 2014, Nellis has been a trustee of the Southern Association of Colleges and Schools Commission on Colleges.
Nellis was announced as the sole finalist for the presidency of Texas Tech University on March 1, 2013. According to news reports, he was recruited for the position, and had not applied. On March 22, the Texas Tech Board of Regents unanimously confirmed him as the university's next president, starting June 15.
Since his arrival, Nellis has promoted moving Texas Tech University forward toward higher levels of national prominence as a major public research university. He has advocated for continued quality enrollment growth (including stronger advocacy for national and international student recognition), accelerated research expenditures and faculty recognitions, creating a more engaged institution while promoting industry and community partnerships, with a commitment toward global connections and creativity while seeking external revenue sources to invest in the university enterprise. Under Nellis' leadership, Texas Tech was named in 2014 an APLU Innovation and Economic Prosperity University. Texas Tech also achieved Tier One Carniege Designation for the highest research category at the conclusion of his presidential term.
Following a candidacy for the presidency at the University of Wyoming, during which he expressed frustration about Texas Tech's governance structure, Nellis announced his resignation from the Texas Tech presidency on January 8, 2016. The university later announced that he would continue on as a tenured university honors professor and work on university strategic initiatives.
Nellis was announced as the next president of Ohio University on February 22, 2017. His presidency began on June 12, 2017.Leadership Award, Dialogue Institute
Alumni Award of Excellence, University of Idaho
Honorary Alumni Award, University of Idaho
Fellow, American Association for the Advancement of Science
Fellow, Explorers Club, New York City
Distinguished Mentor Award, National Council for Geographic Education
Fellow, Royal Geographic Society
Young Research Scholar Award, Institute of British Geographers
Distinguished Alumni Fellow, Oregon State University
Distinguished Alumnus Award, Department of Geosciences, Oregon State University
Outstanding Teaching Award, Kansas State University
University Advisor of the Year Award, Kansas State University
Gilbert Grosvenor Geographic Education National Honors, Association of American Geographers
John Fraser Hart Award for Excellence in Research, Association of American Geographers
Outstanding Contributions Award in Remote Sensing, Association of American Geographers
Phi Beta Kappa, Golden Key, Pi Kappa Phi, Sigma Xi, Mortar Board, Gamma Theta Upsilon
President (2002-2003), Association of American Geographers
President (1994), National Council for Geographic Education
President, (1999-2000) Gamma Theta Upsilon (International Geographic Honor Society)
Mortar Board, Forum Chapter, inducted as member March 2015
Nellis met his wife Ruthie as an undergraduate at Montana State. She was from Pennsylvania and became a librarian. As a librarian, she oversaw a science library at Kansas State, and the medical school library at West Virginia. She also worked in K-State's commercialization initiative, and was project manager on several major library building projects at West Virginia. Married in 1975, the couple has two sons, Jonathan and Jason.