Short story fiction is a brilliant artform -- little nuggets of literary goodness, just long enough to tell the tale, pack an emotional wallop, and move on. Short stories might seem simple, but they are tough to master. Some writers excel at them better than most, and their short tales are arguably their finest achievements. Here are some of my favorites:
Edgar Allan Poe - The man credited with inventing the detective tale was one of the first to make a mark in the short story market. My favorite is "The Tell-Tale Heart," a work of genius that will forever stand the test of time.
Harlan Ellison - Love him or hate him, his award-winning speculative fiction is some of the best in any genre. I never tire of reading "Paladin of the Lost Hour," "I Have No Mouth, And I Must Scream," and all the rest.
O. Henry - Known for their wonderful twist endings, his short stories are full of wit and charm, delighting readers of all ages.
H. P. Lovecraft - One of the most influential writers of what has come to be known as "weird fiction," this master of the macabre may not have been a household name during his lifetime but his new-mythology-laced stories continue to inspire writers, filmmakers, and other artists today.
Stephen King - Best known for his novels, King's short stories are under-appreciated gems. His early collections -- Night Shift and Skeleton Crew -- are especially excellent.
Neil Gaiman - There is arguably no better living fantasy writer today than Mr. Gaiman. He has gained fame as a comic book writer, a novelist, a children's book writer, and even as a screenwriter, but his short fiction is phenomenal as well.
Isaac Asimov - The prolific writer really knew how to tell a story in its simplest, yet most entertaining, form. Some of his interconnecting short stories are my favorites, in which each subsequent story builds on what came before. "Nightfall," one of his greatest stories, was both a short story and later expanded into a full novel. While the novel was great, his shorter version is near perfection.
There are many others. Let me know of any that are your particular favorites.