| Louis Vail | |
| Birth Date: | 18 September 1870 |
| Birth Place: | Philadelphia, Pennsylvania, U.S. |
| Alma Mater: | Penn Law School |
| Player Positions: | Quarterback |
| Player Sport1: | Football |
| Player Years2: | 1889–1893 |
| Player Team2: | Penn |
| Player Years3: | 1895 |
| Player Team3: | Duquesne Country & Athletic Club |
| Player Sport4: | Baseball |
| Player Years5: | 1891–1892 |
| Player Team5: | Penn |
| Coach Years1: | 1894 |
| Coach Team1: | Illinois |
| Coach Years2: | 1895 |
| Coach Team2: | Case |
| Coach Years3: | 1895 |
| Coach Team3: | Duquesne Country & Athletic Club |
| Overall Record: | 4–5 (college) |
Louis De Pui "Bucker" Vail (September 18, 1870 – December 16, 1948) was an American football player and coach. Vail played football and graduated from Germantown Academy.[1] He attended the University of Pennsylvania, receiving both his A.B. and his LL.B.[2] He was a member of Delta Phi Fraternity. Vail played football at Penn as a quarterback from 1889 to 1893.[3] Vail also played baseball at Penn in 1891 and 1892.[4]
Vail served as the fourth head football coach at the University of Illinois at Urbana–Champaign, coaching for one season in 1894 and compiling a record of 4–4.[5] Vail coached at Case School of Applied Science for one game in 1895 before the season was cancelled.[6] Later that year, he served as player-coach of the Duquesne Country and Athletic Club football team.[7]