Arthur Wynne, born in Liverpool in 1862, is the inventor of crosswords as we know them today. He was an editor and puzzle creator in Britain and America. He created the "Word-Cross Puzzle" in 1913, after being asked by the New York World to create a new puzzle for their newspaper.
He based the puzzle on a childhood game called Magic Squares. It was diamond-shaped and had no black spaces, but the puzzle was very much the same as it still is now - inter-connected words with "across" and "down" clues. The first "Word-Cross" was published on December 21st, 1913. You can have a go at it yourself here.
Soon it evolved into square- or rectangular-shaped "crosswords" with black spaces as we know them today. Arthur Wynne published the first crossword book in 1924.
Crosswords first appeared in Britain in February 1922 in "Pearsons Magazine". The Sunday Express was the first UK newspaper to publish a crossword, on November 2nd, 1924, as an adapted Wynne puzzle.
Several crossword experts were recruited into code-breaking activities during World War II at Bletchley Park in England.
Arthur Wynne died in 1945.