Jeffrey Francis Williams (born 6 June 1972) is an Australian-born former left-handed pitcher who played for the Hanshin Tigers baseball team.

Willams was credited with two saves during the tournament, including the semi-final game against Japan where he prevented the Japanese team from scoring, preserving the 1–0 win.

While with the Dodgers in 2000 and 2001, the tandem of Williams and fellow Australian Luke Prokopec gained considerable popularity in the Los Angeles area.

In 2005, he reverted to the role of set-up pitcher, appearing in 75 games for the Hanshin Tigers, who won the championship.

Their formation was given the nickname JFK by their team, using their initials from their pitching order (Jeff, Fujikawa, Kubota).

On 13 December 2007, Williams was named as a player linked to performance-enhancing drug use in the Mitchell Report for Major League Baseball.