Last week the Los Angeles Dodgers designated outfielder Jason Heyward for assignment. If he doesn’t hook on with another team, he will be just the third player in major league history to hit a home run in his first big-league at-bat and also homer in his final at-bat. The other two are Paul Gillespie and John Miller.

Since 1900, 134 players have hit a home run in their first at-bat. Two members of the Hall of Fame – Earl Averill and Hoyt Wilhelm – christened their careers with home runs. Wilhelm, a pitcher, homered on April 4, 1952, and then played 21 years without ever hitting another one. Heyward joined that group on Opening Day of 2010 when he hit a three-run shot off Carlos Zambrano of the Chicago Cubs.

Since 1900, 59 players have hit a home run in the final at-bats of their careers, including Ted Williams and  Mickey Cochrane–technically. Williams put an exclamation point on the end of his career by slamming his 521st round-tripper. But while Cochrane homered in his final official at-bat, he was beaned in his next plate appearance, suffering a fractured skull that ended his career.

The last time Heyward batted, he hit a three-run, pinch-hit home run off Andrés Muñoz of the Seattle Mariners that provided the difference in a 6-3 Dodger victory.

On September 11, 1942, Gillespie, a backup catcher with the Chicago Cubs, kicked off his career with a home run off Harry Feldman of the New York Giants. On September 29, 1945, Gillespie homered off Rip Sewell of the Pittsburgh Pirates in the final at-bat of his career. Gillespie wrapped up his career with only six home runs.

That leaves John Miller, and his is quite a story. On September 11, 1966, Miller made his major league debut with the New York Yankees and homered off Lee Stange of the Boston Red Sox in his first at-bat. Four years later, Miller was playing for the Dodgers when he hit a home run in his final at-bat against Jim Merritt of the Cincinnati Reds.

Making Miller’s accomplishment even more remarkable is the fact that he hit only two home runs in his entire career.

“I don’t remember that but I’m sure it happened,” Miller said of his feat.

Miller appeared in just 32 games in his career, six the Yankees in 1966 and 26 with the Dodgers in 1969.

Things could have turned out differently for Miller. “I was in the on-deck circle in the last game of the season, but the guy in front of me made an out,” Miller said. According to Retrosheet, Miller’s last game was September 27, 1969, but it wasn’t, as Miller said, the final game of the season. He entered the game to pinch-hit for Jim Brewer in the bottom of the 11th inning against lefty Ron Bryant of the San Francisco Giants. But when the Giants brought in righty Don McMahon, the Dodgers countered with lefty-swinging Len Gabrielson as a pinch-hitter for Miller.

An unexpected circumstance during the off-season sealed the deal on Miller’s odd achievement.

“I had a falling out with the general manager Al Campanis during the winter. They were going to send my contract back to Spokane, which was their Triple-A club, or I had an opportunity to go to Japan,” Miller said. “At that point, I wasn’t making a lot of money, so I took the opportunity to go to Japan.”

John Miller’s unique accomplishment just might stand forever. Heyward may hook on with another team, and I hope he does. But in any event, he has 180 home runs to his credit.

(All statistics are from Baseball Reference and Baseball Almanac; all game details are from Retrosheet. The quotes from John Miller are from my telephone interview of June 22, 2010.)

(I edited this post after initial publication following a comment from an intrepid reader reminding me of the details of Mickey Cochrane’s final plate appearance.)