Dennis Lee Rasmussen (born April 18, 1959 in Los Angeles, California) is a former starting pitcher for Major League Baseball's San Diego Padres (1983 and 1988-91), New York Yankees (1984-87), Cincinnati Reds (1987-88), Chicago Cubs (1992) and Kansas City Royals (1992-93 and 1995). He batted and threw left-handed.

In 1986, pitching for the New York Yankees, his batting average against of .217 was 2nd best in the AL.

In 1988, his 14-4 record with the Padres tied him with Gaylord Perry for the team single season Won-Loss record (.778).

In 1990, he led the National League in Home Runs Allowed with 28.

In a 12-season career, Rasmussen posted a 91-77 record with 835 strikeouts and a 4.15 ERA in 1460-2/3 innings pitched.

In a San Diego Padres telecast on April 30, 2007, color commentator Mark Grant mentioned that former player and scout Pat Dobson nicknamed Rasmussen "Count Full Count" due to him frequently getting opposing batters into full counts.