They are named after the company that makes them, Mars Incorporated.
A candy bar that is named after a red planet is the Mars bar. The company also has a candy bar called the Milky Way.
The company was Mars.
Mars
Baby Ruth. (Google it)
That is what the company of the candy wanted it to be named, beyond the name, Mars the Roman god and Mars the candy bar have little in common.
The Mars candy bar has this logo.
"Snickers" is a popular candy bar containing chocolate, peanuts and caramel made by the Mars Candy company. It was named after the Mars family's favorite horse.
Snickers is produced (and was invented) by Mars, Inc. one of the oldest and biggest names in the American candy business.
The 3 Musketeers Bar was first introduced in 1932 by the M & M - Mars Company.
Mars bar. I don't think it's common today, but it existed at one time. That's where the M&M/Mars candy company gets it's name.
A candy bar is called Mars. The mars candy bar is from the creator of M&M's. The creator of Mars Bars also makes the small chocolate called the Milky Way, which was at one point thought to be Cadburys.