From his playing days in Northern California’s Livermore National Little League through a 22-year Major League career, the baseball journey enjoyed by Randy Johnson has seen him crisscross the United States and land in Cooperstown, N.Y., with his election to the Baseball Hall of Fame.

Mr. Johnson was elected as a first-ballot Hall-of-Famer along with fellow former Cy Young Award winners Pedro Martinez and John Smoltz. Craig Biggio joins the pitching trio as a member of the 2015 class entering the Professional Baseball Hall of Fame and Museum.

Through more than two decades on MLB mounds, Mr. Johnson, standing 6-foot-10, became known as the “Big Unit.” Born Sept. 10, 1963, in Walnut Creek, Calif. – a San Francisco suburb – the California District 57 product was one of the dominant pitchers of his era, posting three 20-win seasons (1997, 2001-02) and winning five Cy Young Awards, including a record-tying four straight (1995, 1999-2002).

Breaking into the Majors with the Montreal Expos in 1988 (the franchise moved to Washington and became the Nationals in 2005), Mr. Johnson also pitched for the Seattle Mariners, Houston Astros, Arizona Diamondbacks, New York Yankees and San Francisco Giants.

Mr. Johnson was a 10-time all-star and was chosen to start the all-star game on four occasions. He led his league in strikeouts nine times; third-most all-time behind Walter Johnson (12) and fellow Little League graduate Nolan Ryan (11). He holds the all-time record in that category with a career mark of 10.6 strikeouts per game.

In 2002, Mr. Johnson won the National League’s Pitching Triple Crown for leading the league in wins (24), ERA (2.32) and strikeouts (334). He posted six 300-strikeout seasons, tied with Mr. Ryan for most ever, and his career total of 4,875 strikeouts ranks him second all-time.

The imposing left-hander appeared in 11 postseason series over eight seasons with the Mariners, Astros, Diamondbacks and Yankees, posting 7-9 record with 3.50 ERA in 19 appearances. He struck out 132 batters in 121 postseason innings, and was named co-MVP of the 2001 World Series after going 3-0 for the World Champion Diamondbacks.

The Baseball Writers’ Association of America 2015 Hall of Fame ballot, released Nov. 24, features 34 names, including 17 holdovers from previous elections and 17 newcomers. Former Major Leaguer Mike Mussina, a member of the Little League International Board of Directors and the 2014 Little League Hall of Excellence enshrinee, received 135 votes in his second year of eligibility (24.6 percent). To be elected, candidates must appear on 75 percent of all ballots cast.

The Class of 2015 will be inducted on July 26 in Cooperstown.