Randy Savage (real name Randy Poffo, and incidentally the real life brother of "The Genius" Lanny Poffo) was a former baseball player who decided to give professional wrestling a go after his baseball career ended. He began wrestling for smaller promotions in the 1970s and was hired by the World Wrestling Federation in the early 1980s.
He was a heel for many years after his WWF debut, mistreating his valet, Miss Elizabeth, and using cowardly tactics whenever possible to beat his opponents.
His first feud of any significance was with Ricky "The Dragon" Steamboat, one of the more popular figures in the WWF at the time. Savage had recently won the Intercontinental Championship from Tito Santana, and Steamboat began challenging him for the belt. In one match, Savage hit Steamboat across the throat with the ring bell, causing Steamboat a serious injury (in character). Upon Steamboat's return, he would follow Savage to house shows around the country and torment him, usually interfering in his matches. This all led to a blowoff match at Wrestlemania III between the two, a match which is widely considered one of the best professional wrestling matches of all time. Steamboat won the Intercontinental belt here to one of the loudest ovations you'll ever hear.
Savage turned babyface soon after, and in under a year's time he was the second most beloved wrestler (behind only Hulk Hogan) in the WWF. At Wrestlemania IV, he was a participant in the tournament to crown a new WWF Champion (the title had been vacant), and Savage beat Ted DiBiase in the finals to win his first WWF Championship.
Hulk Hogan does not like to sit in the limelight long, however, and so Savage was turned heel a few months later so that Hogan could face the champ for the belt at Wrestlemania V. Hogan beat him there, of course, and Savage spent the next few years staying in that heel role (known as the "Macho King" Randy Savage).
He lost a "loser must retire" match to the Ultimate Warrior at Wrestlemania VII, and accomplished a minor miracle by turning face after the match, as his manager at the time, Sensational Sherri, began to beat him up for losing. Who should run out of the stands but Miss Elizabeth, who ran off Sherri and, in a great moment, embraced Savage in the middle of the ring. Savage soon asked Elizabeth to marry him, and the ceremony took place at SummerSlam '91. (The two had been married since 1984 in reality, but who's counting? They later divorced.)
Since retirements in wrestling never last, he returned to the ring soon after as a babyface, winning his second WWF Championship from Ric Flair at Wrestlemania VIII (1992). He languished in the WWF for a few more years (as a wrestler and announcer) before following his good friend Hulk Hogan to World Championship Wrestling in 1994.
He wrestled in WCW for the next five years, both as a babyface and heel at various points, and winning the WCW World Title on several occasions. Part of the initial anti-nWo contingent, he later joined the nWo ranks--one of the things that killed most of his heat. His in-ring presence diminished greatly and with the fans not responding at all, he finally disappeared for good in 1999.