Samuel Loyd (January 31, 1841 - April 10, 1911) was an American puzzle author and recreational mathematician.
Loyd claimed to have invented the famous fifteen puzzle. He also authored a number of chess problems, often with witty themes of solutions. Following his death, his book Cyclopedia of Puzzles was published (1914).
One of his best known chess problems is the following. White is to move and mate black in five moves against any defence:
Loyd bet a friend of his that he could not pick a piece that didn't give mate in the main line, and when it was published in 1861 it was with the stipulation that white mates with "the least likely piece or pawn". Loyd called the problem "Excelsior" after the poem by Henry Wadsworth Longfellow. The solution can be found by clicking on the above diagram.