Eliézer Jesús Alfonzo (/ɪˈliːzər/; Spanish pronunciation: [eˈljeθeɾ]; born February 7, 1979) is a Venezuelan professional baseball catcher.

Alfonzo made his professional debut as a third baseman for St. Louis' affiliate in Dominican Summer League he batted .325 in 24 games.

He spent remainder of the 2000 campaign at the Class-A Beloit Snappers hitting a combined 26 doubles, 10 home runs and 48 RBIs in 109 games.

He logged his final year in the Milwaukee chain in 2002, splitting time with Class-A High Desert Mavericks and Double-A Huntsville Stars.

In 2004, Alfonzo was selected to the Florida State League All-Star team during lone campaign in Marlins organization.

Alfonzo filled in for veteran catcher Mike Matheny, who was sidelined with symptoms following a concussion for the rest of the 2006 season.

He went 1-for-11 with an RBI in five games with San Francisco, he lost the competition for the backup catcher position and was sent back down to Triple-A.

On May 1, 2008, Alfonzo was suspended for 50 games for testing positive for a performance-enhancing substance in violation of Major League Baseball's Joint Drug Prevention and Treatment Program.

[4] On June 29, 2010, the Mariners designated Alfonzo for assignment to make room for Bard, who was coming off the disabled list.

He was called up to the major leagues on July 15, 2011, from the Rockies' AAA farm team, the Colorado Springs Sky Sox.

In September 2011, Alfonzo became the second major league player (Manny Ramirez was the first) to be suspended 100 games for a second positive drug test.

He had received an invite to Major League camp, but contracted Dengue fever in his native Venezuela during the offseason.