Ralph S. Mueller is credited with the invention of the alligator clip.
Born in Iowa in 1877, Mueller took a degree in electrial engineering from the University of Nebraska in 1898. He began work for the Kellogg Switchboard Company in Chicago, which transferred him to Cleveland in 1904. In 1908, he founded the Mueller Electric Company in that city. According to the company's website, their first product was the alligator clip. However, the earliest patent I can find for him was for a "swivel plug" filed in 1916, granted in 1922 and assigned to the Bejamin Electric Manufacturing Company. He didn't receive a design patent for his "test clip" until 1920.
So, it's interesting that his first patent was not assigned to his own company, and that if his first product in 1908 was the alligator clip, he didn't bother to apply for patent protection until 1919. In any event, his clip certainly ran rings around the competition at the time (search google patents for "test clips" to see some overly complicated and awkward alternatives being patented around this time). The clips were big sellers for voltmeter leads and telephone linesmen's clips as the country was being wired for this new communication device. In the 1950's, the company shared the alligator clip market with only 2 other American companies. By 1962, the company was producting 100,000 clips and 33,000 insulators each day. No wonder that Mueller was known as "the skipper of the clipper" (the title of his 1957 autobiography). In 2009, under the helm of Mueller's great-grandson the company moved to Akron, Ohio, where it eventually declared bankruptcy. Since 2011, it has been a Desco Corporation company.
Mueller himself was a great philanthropist, particularly towards Nebraska. When he attended university there, no tuition was charged except for a $5 fee and lab charges. Mueller once remarked:
"Young people just naturally take for granted everything that is done for them. I was not even a resident of Nebraska but for a five dollar matriculation fee the State of Nebraska gave me my education which I promptly carried away with me to use in other states. I later came to realize that the tax payers of Nebraska had been very generous to me. Unquestionably my education helped fortune to smile on me and so, in an effort to balance the account I have, thru the years, chipped in practically every time Nebraska has passed the hat. In addition I have sponsored three major projects of my own."
Those three major projects were the Mueller Planetarium at the University of Nebraska State Museum, the Health Science Galleries, and Mueller Tower, a carillon bell tower which still stands to the west of the museum.
Tragically, in 1966 at the age of 89, Ralph Mueller threw himself off of the fire escape on the fifth story of the building he lived in.
I'm indebted for much of the above information to an article written by Pat Galbincea in The Plain Dealer. That newspaper also has a series of interesting online articles on Northeast Ohio creations: Inventions with local roots. Among other things, these include the Thompson submachine gun, the padded bicycle seat, the alkaline battery and Lifesavers candy!