Kenner
Kenner Toys first received the license to create Star Wars action figures in 1977. By making the figures smaller than other dolls--3.75 inches each--they could charge less for them, letting kids afford them more easily.
Snafu
Production troubles prevented Kenner from getting the dolls out in time for Christmas 1977. Instead they issued "Early Bird Certificates" that let people pick up the first four figures when they were finally released.
Success
Despite the early misfire, Kenner's line was a huge success, and continued from 1978 until 1985.
Hasbro
Kenner was eventually bought up by Hasbro toys, which produced a new line of Star Wars figures starting in 1995. The "Power of the Force" line featured more muscular figures than those of the 1970s.
Prequels
Hasbro continued producing Star Wars figures through the re-release of the original trilogy in 1997, and created new figures to coincide with the three prequels released from 1999 to 2005.