The correct term for the little plastic people that are part of the LEGO toy system.
In 1974, the first LEGO figures were introduced. These were approximately 9 blocks tall and were made of a combination of regular LEGO blocks and specialized head and arm pieces. These are not called minifigs. They were very popular at the time, but are no longer being made.
In 1978, LEGO released the minifig figure. Minifigs feature movable arms and legs (earlier figures had legs that were fixed and joined together), and were approximately half as tall. Thanks to the ingenuity of the LEGO product development team, minifigs are poseable, will attach to LEGO blocks both while standing and sitting, and can hold both regular blocks and specialized implements in their hands.
The first minifigs were part of the town series and looked and dressed much like you and I. Since then, LEGO has released minifig astronauts, knights, peasants, wizards, witches, skeletons, pirates, sailors, soldiers, aliens, ninjas, cowboys, Native Americans, even Star Wars characters.
The first minifigs to feature a different face from the beloved smile were the LEGO pirates, some of whom featured eyepatches and stubble.
Dozens of different tools toys and implements have been made for a minifig to use in his microcosm, such as a wrench, briefcase, musket, rifle, bow, sword, cutlass, dagger, mirror, megaphone, hammer, binoculars, not to mention other various less specific items.