The Ultimate Fighting Championship (later renamed UFC 1: The Beginning) was the first mixed martial arts event by the Ultimate Fighting Championship (UFC), held at the McNichols Sports Arena in Denver, Colorado, United States, on November 12, 1993. The tournament featured fights with no weight classes, rounds, or judges. The three rules – no biting, no eye gouging, and no groin shots – were to be enforced only by a $1,500 fine. The match only ended by submission, knockout, or the fighter's corner throwing in the towel, although the referee stopped the first fight at 26 seconds.

UFC 1: The Beginning

UFC 2: No Way Out (later renamed UFC 2 or The Ultimate Fighting Championship 2) was a mixed martial arts (MMA) event held by the Ultimate Fighting Championship (UFC) on March 11, 1994, at Mammoth Gardens in Denver, Colorado. The tournament had no weight classes or weight limits. Matches had no time limit or rounds, therefore no judges were used. Competitors could only win a match by submission, by the opponent's corner throwing in the towel, or by knockout.

UFC 2: No Way Out

UFC 23: Ultimate Japan 2 was a mixed martial arts event held by the Ultimate Fighting Championship on November 19, 1999 at Tokyo Bay NK Hall in Tokyo, Japan.