Oakland Hall — LEED Gold-certified dormitory on North Campus. Opened in 2011. Named for Oakland, MD, the county seat of Garrett County.
Observatory — Located at 3255 Metzerott Road, adjacent to the main campus. Dedicated in November 1964. Originally housed two telescopes. Frequently hosts open houses for visitors. For more information, visit the Observatory's history page.
ODK Fountain — Central feature of McKeldin Mall. Constructed in 1990 and named by the campus chapter of Omicron Delta Kappa (ODK) in 1997. Each tier of the fountain represents one of the areas of leadership from which ODK members are drawn. More information about the fountain and a list of the names surrounding it may be found here.
Olympians — A number of athletes from the University of Maryland have participated in the Olympics, including:
- Nataly Arias, 2012 and 2016, women's soccer (Colombian team)
- Bjorn Andersen, 1960, pole vault (Danish team)
- Desmond Armstrong, 1988 and 1992, men's soccer
- Vicky Bullett, 1988 (gold medalist) and 1992 (bronze medalist), women's basketball
- Danny Califf, 2000, men's soccer
- Ken Clark, 1948, canoeing
- Carin Cone, 1956, swimming (Australian team), silver medalist in the 100-meter backstroke
- Mark Coogan, 1996, marathon
- Arthur E. Cook, Jr., 1948 (gold medalist), shooting
- Rick Curl, swimming, 1996, 2000 (coach)
- Vernon Davis, 2010, curling, honorary captain
- Dominique Dawes, 1996 and 2000, gymnastics; bronze medalist in floor exercise and a team gold medal in all-around competition in 1996
- Maurice Edu, 2008, men's soccer
- John Eiseman, 1948 and 1952, canoeing
- Stephanie Fee (UMD assistant field hockey coach 2016-present), 2016, field hockey
- Ernie Fisher, 1956, wrestling
- Paula Girven, 1976, high jumping
- Gary Goodner, 1968, swimming (Puerto Rico team)
- Lea Hakala, 1984, women's basketball (Finnish team)
- Erika Hansen, 1988 and 1992, swimming (5-time U.S. National Champion, assistant swimming coach 2004-2005)
- Tara Heiss, 1980, women's basketball
- Frederic "Rip" Hewitt, 1948, men's field hockey
- Kelli Hill, 2000 and 2004, gymnastics (head coach)
- Thomas Hong, 2018, speed skating
- Tom Horton, 1948 and 1952, canoeing
- Ekene Ibekwe, 2012 and 2016, men's basketball (Nigerian team)
- Sarunas Jasikevicius, 2000 (bronze medalist), 2004, 2008, and 2012, men's basketball (Lithuanian team)
- Katie Kauffman-Beach, 1996, field hockey
- Kris Kirchner, 1980, women's basketball
- Irene Knox, 1932, shooting (qualified, did not compete since there was no women's competition in rifle this year)
- Howard B. Labow, 1980 (athlete) and 2000 (assistant coach), fencing coach (Israeli team)
- Thea LaFond, 2016, track and field (Dominica team)
- John Maddocks, 1984, sailing (British team)
- Kerry McCoy (UMD wrestling coach, 2009-2019), 2000 and 2004, wrestling
- Tom McMillen, 1972 (silver medalist), men's basketball
- Missy Meharg, 1996, field hockey (coach)
- Linda Murray, 1972, kayaking; Linda Murray Dragan, 1976 and 1980, kayaking
- Ashley Nee, 2016, canoe and kayak
- Renaldo Nehemiah, 1980, track
- Katie O'Donnell Bam, 2012 and 2016, field hockey
- Jasmina Perazic, 1984, women's basketball (Yugoslavian team)
- Micha Powell, 2016, track and field (Canadian team)
- Lauren Powley, 2008, field hockey
- Dina Rizzo, 2008, field hockey
- Robbie Rogers, 2008, men's soccer
- Chris Seitz, 2008, men's soccer
- Steve Sheppard, 1976 (gold medalist), men's basketball
- Danielle Siebert, 2020, track and field (coach)
- Sara Silvetti, 2008, field hockey (alternate)
- Keli Smith, 2008 and 2012, field hockey
- Todd Sweeris, 1996 and 2000, table tennis
- Andrew Valmon (UMD track and field coach, 2004-present), 1988 (gold medalist), 1992 (gold medalist), and 2012 (coach) track
- Charles "Buck" Williams, 1980, men's basketball
- Jill Witmer, 2016, field hockey
Olympics, Hosting —The university was part of the Washington-Baltimore Regional 2012 Coalition that put forward a bid to hose the 2012 Olympics. The athletes would have been housed at the University, and the National Mall in D.C. was proposed as the site for the opening ceremonies.
Omicron Delta Kappa — The campus chapter of this national leadership fraternity, known as the Sigma Circle, was founded on February 2, 1927. More information about the Sigma Circle may be found here. See also ODK Fountain.
OMSE — See Multi-Ethnic Student Education, Office of
Online Catalog — The University of Maryland Libraries dedicated the first version of the online catalog of their holdings, created by a vendor named Geac, in April 1987.
Opening Day — The Maryland Agriculture College, as the University of Maryland was then known, opened its doors to students on October 5, 1859. The freshman class consisted of 34 male students, the first students to enroll were the four sons of Charles Benedict Calvert, the college's founder.
Orioles — The Baltimore Orioles played an exhibition game against the Terps on Shipley Field in Bob "Turtle" Smith Stadium on April 12, 1982. One of the stars that took the field that day was the legendary Cal Ripken, Jr.
Oscar Winners — See Academy Award winners