Adam Thomas Eaton (born November 23, 1977 in Seattle, Washington) is a Major League Baseball pitcher with the Colorado Rockies.

Eaton graduated from Snohomish High School in 1996 where he went 8–0 with a 0.67 earned run average (ERA) as a senior, and earned second team High School All-America honors from Baseball America. Ranked the No. 1 prospect in the Pacific Northwest by Baseball America, Eaton was scheduled to attend the University of Washington, but was drafted by the Philadelphia Phillies with the 11th pick in the first round of the 1996 Major League Baseball Draft.

After signing, the Phillies assigned Eaton to their team in the A-level South Atlantic League, the Piedmont Boll Weevils. Though he spent a month on the disabled list during the 1997 season, he posted a 5–6 record with a 4.18 ERA. Though his ERA went up a quarter of a point to 4.43 in 1998, his record was 9–8 as he struck out 89 batters in 132 innings at Clearwater. He was also named a mid-season All-Star in the Florida State League. 1999 saw Eaton climbing his way up the rungs of the Phillies' farm system, starting the year at Clearwater, then earning promotions to Reading and Scranton/Wilkes-Barre. Between the three levels, Eaton posted a 11–10 record and a combined 3.34 ERA, striking out 127 in 167 innings. For his accomplishments, Eaton was honored as the recipient of the Paul Owens Award, given to the top Phillies' minor league pitcher each season. At the end of the season, before his first major league appearance, Eaton was traded with Carlton Loewer and Steve Montgomery by the Phillies to the San Diego Padres for Andy Ashby. He posted a 4–1 record in ten starts for the Mobile BayBears.