From BR Bullpen
A bobblehead is a small figurine representing a baseball player with an oversized head. The head is mounted on springs so that it can sway gently when touched. Bobbleheads were originally created as souvenirs in the 1950s and 1960s and were generic figures, wearing a team uniform but not representing a specific player. For example, Mr. Met has the typical body shape of a bobblehead doll from that era, as does the "Mr. Red" figure appearing on the Cincinnati Reds logo.
Bobbleheads were revived in the late 1990s, first as a nostalgia item, and then became very popular when depicting the likenesses of specific players. They are typically given away to fans as part of promotions on specific days, but some are manufactured to be sold directly to collectors. While originally linked to baseball players, bobbleheads now exist for athletes of all types, and baseball teams have become very creative in designing these items, creating them with the likeness of historical baseball players, team mascots, and other figures linked to the game. For example, the minor league Lowell Spinners once gave out a bobblehead of writer Jack Kerouac, a local son who started out his career as a sportswriter before becoming one of the greatest American novelists of the 1950s and 1960s, while the Seattle Mariners gave out a "Larry Bernandez" bobblehead in the likeness of the alter ego of pitcher Felix Hernandez, made famous in a television commercial for the team.