| Harold Olsen | |
| Birth Date: | 12 May 1895 |
| Birth Place: | Rice Lake, Wisconsin, U.S. |
| Death Place: | Rice Lake, Wisconsin, U.S. |
| Player Sport1: | Basketball |
| Player Years2: | 1914–1917 |
| Player Team2: | Wisconsin |
| Coach Sport1: | Basketball |
| Coach Years2: | 1918–1919 |
| Coach Team2: | Bradley |
| Coach Years3: | 1919–1922 |
| Coach Team3: | Ripon |
| Coach Years4: | 1922–1946 |
| Coach Team4: | Ohio State |
| Coach Years5: | 1946–1949 |
| Coach Team5: | Chicago Stags |
| Coach Years6: | 1950–1952 |
| Coach Team6: | Northwestern |
| Coach Sport7: | Football |
| Coach Years8: | 1919–1921 |
| Coach Team8: | Ripon |
| Coach Sport9: | Baseball |
| Coach Years10: | 1919 |
| Coach Team10: | Bradley |
| Overall Record: | 311–241 (college basketball) 95–63 (BAA) 13–6–1 (college football) 0–1 (college baseball) |
| Tournament Record: | 6–4 |
| Championships: | Basketball 5 Big Ten (1925, 1933, 1939, 1944, 1946) NCAA Runner-up (1939) 3 NCAA Final Four (1944–1946) |
| Awards: | Helms Foundation All-American (1917) |
| Baskhof Year: | 1959 |
| Baskhof Id: | harold-olsen |
| Cbbaskhof Year: | 2006 |
Harold G. Olsen (May 12, 1895 – October 29, 1953) was a college men's basketball coach. The Rice Lake, Wisconsin native was the head coach of the Ohio State University from 1922 to 1946. That year, he became the first head coach of the BAA's Chicago Stags, where he coached almost three seasons before being replaced by Philip Brownstein. Olsen also coached at Northwestern University (1950–1952).
While playing at University of Wisconsin–Madison (1914–1917), Olsen was named to the All-Big Ten twice for basketball.[1] After graduating from Wisconsin, he began his coaching career at Bradley University and Ripon College. In 1922, Olsen followed George Trautman as head coach of the Ohio State University. In 24 years he guided the Buckeyes to a 259–197 record, as well as five Big Ten championships (1925, 1933, 1939, 1944, 1946). He served as a chair on the NCAA Basketball Committee. Olsen helped initiate the 10-second rule in 1937, which requires teams to advance the ball over the center line within 10 seconds of gaining possession. In 1939, Olsen spearheaded efforts to create the NCAA postseason national playoffs, now known as the NCAA tournament, one that could compete with the National Invitational Tournament, which started play in 1938 with games hosted at Madison Square Garden in New York. The first NCAA tournament in 1939 saw Northwestern University host eight teams. Oregon beat Ohio State to become the first tournament champion in a format that has expanded several times to go with its popularity as the premier tournament for college basketball.
In 1959, he was inducted to the Naismith Memorial Basketball Hall of Fame as a contributor.
|-| style="text-align:left;"|CHS| style="text-align:left;"||61||39||22||.639|| style="text-align:center;"|1st in Western||11||5||6||.455| style="text-align:center;"|Lost in BAA Finals|-| style="text-align:left;"|CHS| style="text-align:left;"||48||28||20||.583|| style="text-align:center;"|3rd in Western||5||2||3||.400| style="text-align:center;"|Lost in BAA Semifinals|-| style="text-align:left;"|CHS| style="text-align:left;"||49||28||21||.571|| style="text-align:center;"|3rd in Western||2||0||2||.000| style="text-align:center;"|Lost in BAA Div. Semifinals|- class="sortbottom"| style="text-align:left;"|Career| ||158||95||63||.601|| ||18||7||11||.389