Here's a look at some of the candidates:
The Kid is a 13-time All-Star who ranks sixth on the all-time homer list, with 630. He played 22 Major League seasons and won 10 Gold Gloves. Although there are no guarantees, Griffey is as close to a lock as there can be.
Closers haven't had an easy time getting plaques in Cooperstown, but Hoffman retired with 601 saves, a record until Mariano Rivera eclipsed it. Hoffman also retired with the highest career strikeout rate of any reliever in history.
One of only five relievers with more than 400 career saves, Wagner finished with 422. That's two behind John Franco for the most by a lefty closer, and he almost certainly would have moved up the list if he hadn't decided to retire with a year left on his contract.
Others who could get votes for the first time are Jason Kendall, Jim Edmonds, Garret Anderson and Brad Ausmus.
Among the holdovers, Piazza appears to have the best chance of breaking through. In the voting by 10-year members of the Baseball Writers' Association of America, one of the best offensive catchers ever (.308 career average, 427 homers, .922 OPS) was named on 57.8 percent of the ballot in his first year of eligibility, 62.2 percent the second and 69.9 percent last time around.
Bagwell, the 1994 National League MVP Award winner and a four-time All-Star, will be on the ballot for the sixth time. In his 15-year career, he hit 449 home runs and compiled a .948 OPS. Bagwell's highest percentage of the vote was 59.6, in 2013. Last year, he tallied 55.7 percent.
Raines, in his ninth year, received a career-high 55 percent last year. He's regarded as one of the best leadoff hitters of his era, a seven-time All-Star who has the most stolen bases of any switch-hitter in history.
Barry Bonds (36.8 percent), baseball's all-time home run leader, and Roger Clemens (37.5 percent), who won a record seven Cy Young Awards, will both appear for the fourth time.
Also remaining under consideration are Curt Schilling (39.2 percent), Edgar Martinez (27 percent) and Mike Mussina (24.6 percent). Alan Trammell (25.1 percent) is in his final year of eligibility, and Lee Smith (30.2) has only one more shot if he doesn't make it this time.
In addition, at the Winter Meetings in Nashville, Tenn., this December, the Veterans Committee will meet to consider the Pre-Integration ballot submitted by the BBWAA's Historical Overview Committee. Under consideration will be candidates whose most significant contributions came before 1947.
The last time the Pre-Integration Committee met, in 2012, former Yankees owner Jacob Ruppert, umpire Hank O'Day and 19th-century catcher Deacon White were inducted.
With the plaques for Biggio, Johnson, Martinez and Smoltz installed on Sunday, it's time to start thinking about who might join them in 2016.