Thomas Edison. Alexander Graham Bell. Steve Jobs. You've almost certainly heard of all of these guys before. But not all inventors become household names. Some, in fact, end up royally screwed over. Here are such some people:
Todd Mills, Doritos Locos Taco: The visionary behind the taco that's swept the nation got to taste one of the first Locos Tacos. But he had been repeatedly pitching the idea of a Doritos taco shell for years before Taco Bell finally responded in 2012. Mills died this Thanksgiving without ever seeing a dime for his troubles. 
Edwin H. Armstrong, FM Radio: Armstrong spared radio listeners from the coarse static of AM radio when he developed the first small network of nicer-sounding FM radio stations. But he also threatened the status quo, and so the the Radio Corporation of America and AT&T lobbied hard to make Armstrong's technology obsolete. The competitors couldn't stop FM from becoming hugely popular, but the legal wrangling that ensued did eventually drive Armstrong to suicide in 1954.
John Walker, Matches: This chemist invented the match by accident when a dried chunk of chemical solution on a mixing stick caught fire. He showed his friends -- who obviously begged him to patent it -- but Walker said the match was "too trivial." Today, 500 billion matches are used every year in the U.S. Trivial, huh?
Alexey Pajitnov, Tetris: Pajitnov invented Tetris at a government-sponsored lab in 1980s Communist Russia, but he saw no profit from one of the most legendary video games in history until he headed to the U.S. in 1996. Only then did Pajitnov begin to collect royalties. Clearly, "in Soviet Russia, Tetris plays you!"
Mikhail Kalashnikov, AK-47: Kalashnikov invented the weapon in Communist Russia in 1947, but he told AFP that he was motivated by service to his country, not by profit. There are now more than 100 million AK-47s in circulation. Kalashnikov earned a lot of accolades from the Motherland but no financial gains.
Harvey Ball, The Smiley Face: No, Ball wasn't the first person to smile, but he did create the iconic design for an advertising company in 1963. Within a decade, more than 50 million pins featuring the smiley face were created. Ball made all of $45 for his design. Not much to smile about. 
Geoffrey Dummer, Microchip: This British engineer presented his novel idea of a microchip at a conference in 1952. But no one expressed interest in the revolutionary technology at the time. Six years later, Texas Instruments patented the idea. D'oh. 
Rosalind Franklin, DNA: We don't mean to suggest that Franklin invented the building blocks of life. But she did discover and capture the first image of DNA. Infamously, however, rival researchers Watson and Crick got the credit and didn't admit that they'd stolen the image for 40 years. 
Unknown, Monopoly: Conventional wisdom has it that Monopoly was created by Parker Brothers right after the Great Depression, presumably to celebrate all the joys of market capitalism. However, historians have found highly similar versions of the game that date back to 1903.
Richard Pearse, Airplane: You read that correctly; the Wright brothers did not invent the airplane. Richard Pearse, a farmer in New Zealand, actually flew a plane several months before the legendary Kitty Hawk lift-off. He also likely flew for 350 yards, compared to the Wright brothers measly 40-yard trip. Additonally, some aviation experts argue that Gustave Whitehead, a German living in Connecticut, flew for 1.5 miles two years before the Wright flight.
Louis Le Prince, Moving Picture: Thomas Edison got all the credit for creating the first moving picture, but it was actually the French inventor Louis Le Prince who first used film to capture street traffic in Leeds, England, in 1888. Le Prince boarded a train in 1890 and was never seen again. And during a legal trial for Edison's claim for the moving picture patent, Le Prince's son was murdered, leading to whispers of a potential conspiracy.
Daisuke Inoue, Karaoke: Inoue, a drummer for a band that allowed audience members to do vocals, first came up with the idea for Karaoke -- Japanese for "empty orchestra" -- in 1971. Inoue couldn't make a gig one night, so he recorded the background music on tape instead. He failed, however, to submit a patent and make a buck from the device that now fuels a multi-billion dollar industry. 