Ernesto R. Knollin (May 23, 1888 – June 1981) was an American football, baseball, and soccer coach.

Knollin was the head soccer coach at Stanford University in 1918, tallying a mark of 0–2.^[1]

Knollin served as the head football coach at San Jose State University, from 1924 to 1928, compiling a record of 14–22–2.

Knollin was also the head baseball coach at San Jose State, from 1925 to 1928, amassing a record of 27–14–1.^{[citation needed]}