| Jim Fahnhorst | |
| Number: | 55 |
| Position: | Linebacker |
| Birth Date: | 8 November 1958 |
| Birth Place: | St. Cloud, Minnesota, U.S. |
| Height Ft: | 6 |
| Height In: | 4 |
| Weight Lb: | 230 |
| High School: | St. Cloud Technical |
| College: | Minnesota |
| Draftyear: | 1982 |
| Draftround: | 4 |
| Draftpick: | 92 |
| Pastteams: | |
| Highlights: |
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| Statlabel1: | Sacks |
| Statvalue1: | 1.0 |
| Statlabel2: | Interceptions |
| Statvalue2: | 7 |
| Pfr: | FahnJi20 |
James John Fahnhorst (born November 8, 1958) is an American former professional football player who was a linebacker for the San Francisco 49ers in the National Football League (NFL) from 1984 through 1990. He was a member of three Super Bowl champions with the 49ers and started in Super Bowl XIX, XXIII and XXIV. Fahnhorst grew up in St. Cloud, Minnesota and graduated from St. Cloud Tech High School. He played college football for the Minnesota Golden Gophers, earning first-team All-Big Ten honors from AP and UPI in 1981. He is the younger brother of the late former 49ers' tackle Keith Fahnhorst. Graduating with a BA in Psychology, and a minor in Criminology.
Fahnhorst also played two years in the United States Football League (USFL) for coaching legend George Allen in the spring/summer of 1983 and 1984 for the Chicago Blitz and Arizona Wranglers. He is currently a financial advisor and has coached college football at Division III Macalester College and at Wayzata and Maple Grove High Schools in the Minneapolis area.