Lucky Charms is a brand of cereal produced by the General Mills food company of Golden Valley, Minnesota, United States. It first appeared in stores in 1964. The cereal consists of two main components: toasted oat-based pieces and multi-colored marshmallow bits (marbits) in various shapes, the latter making up over 25 percent of the cereal's volume. The label features a leprechaun mascot, Lucky, animated in commercials.
Lucky Charms were created in 1962 by John Holahan. General Mills had challenged a team of new product developers to use the available manufacturing capacity from either of General Mills' two principal cereal products — Wheaties or Cheerios — and do something unique to them. Holahan came up with the idea after a visit to the grocery store in which he decided to mix Cheerios with bits of Brach's Circus Peanuts.
An advertising company employed by General Mills and Company suggested marketing the new cereal around the idea of charm bracelets. Thus the charms of Lucky Charms were born. The mascot, Lucky the Leprechaun (also known as Sir Charms, and originally called L.C. Leprechaun), was also born in 1963, a cartoon character whose voice was supplied by Arthur Anderson until 1992. The oat cereal originally was not sugar coated. After initial sales failed to meet expectations, the oats became sugar coated, and the cereal's success came to what it is known to today. Following launch, the General Mills marketing department found that sales performed dramatically better if the composition of the marbits changed periodically. Various other features of the marbits were also modified to maximize their appeal to the cereal's target of young consumers. In focus groups and market research, more brightly colored charms resulted in better sales than dull or pastel colors. Holahan called Lucky Charms a "lesson in creative marketing." Currently, General Mills conducts frequent "concept-ideation" studies on Lucky Charms.
The first boxes of Lucky Charms cereal contained marshmallows in the shapes of pink hearts, yellow moons, orange stars, and green clovers. The lineup has changed occasionally over the years, beginning with the introduction of blue diamonds in 1975. Purple horseshoes joined the roster in 1984, followed by red balloons in 1989, rainbows in 1992, pots of gold in 1994, leprechaun hats in 1996, shooting stars in 1998, and an hourglass in 2008.
Older marshmallows were phased out periodically. The first shapes to be phased out were the yellow moons and blue diamonds, as General Mills introduced their "Pot of Gold" marshmallow. In 2006, the assortment had changed to purple horseshoes; red balloons; blue half-moons; orange and white shooting stars; yellow and orange pots of gold; pink, yellow, and blue rainbows; two-tone green leprechaun hats; pink hearts (the only shape to survive since the beginning); with the most recent addition being the return of the clovers in 2004. The marshmallows also grew in size in 2004.
Recent changes to the marshmallows include: the star shape took more of a "shooting star" design, the orange 5 pointed star being added together with a white "trail" (though making the 5th point in the star almost invisible). More recently, in late 2005 another different kind of marshmallow was added, the "Hidden Key". It is a solid yellow marshmallow that resembles the shape of an arched door (similar to the shape of a tombstone; flat at the bottom, flat sides with a round top). When liquid is added to the cereal, the sugar inside the marshmallow dissolves and the shape of a skeleton key "appears" as if "by magic". The new tagline for this is "Unlock the door with milk!" This "new" marshmallow type has been used in other kinds of hot and cold cereals, but with mixed success (from characters "hidden" inside a bigger marshmallow to letters appearing). Also to note, this new "Hidden Key" marshmallow only appears in the original variation of Lucky Charms and not in the Chocolate or Berry versions. In early June 2006, General Mills introduced a new Lucky Charms marshmallow, Magic Mirror marshmallows.
In 2008, yellow and orange hourglass marshmallows were introduced (along with a new contemporary for Lucky named the Emerald Elder) with the marketing tagline of "The Hourglass Charm has the power to Stop Time * Speed Up Time * Reverse Time".
In 1991, the star and balloon shape marshmallows were combined for a short time. The red balloon featured a gold six-pointed star; The star was removed at a later date to make the Red Balloon and Star marshmallows separate.
In 1999/2000 a "New Sparkling Rainbow" was added to the mix for a limited time. It was described by General Mills as "a sprinkling of multicolored sugar on a white rainbow marbit." This marshmallow replaced the original rainbow at this time.
In the earliest commercials, Lucky Charms cereal had no theme song; the action was accompanied by a light instrumental "Irish" tune. Before long, however, a simple two-line tag was added:
This simple closer, with the kids usually singing the first line and Lucky singing the second, remained into the '80s. Then, with the addition of the purple horseshoe marbit, it was extended into a jingle that describes the contents of the box:
In 2004, the Leadership Institute along with conservative activist James O'Keefe called for Lucky Charms cereal to be banned from the Rutgers University campus, arguing in a satirical campaign that the cereal is offensive to Irish American students. 
An Actor's Odyssey: Orson Welles to Lucky the Leprechaun, by Arthur Anderson. Albany, 2010. BearManor Media. ISBN 1-59393-522-6.