Which came first, American Bandstand or teen idols? The common consensus seems to be that the presence of the Philadelphia show encouraged the development of the mostly Italian, local teen idol market.
Besides Elvis, still undisputably "The King", the "Big Five" overall, were probably Frankie Avalon, Fabian, Bobby Rydell, Ricky Nelson, and Paul Anka.
Avalon(born Francis Avallone)was managed by Bob Marcucci, co-owner of Philadelphia-based Chancellor Records(of which Dick Clark had a controlling interest in at the time, until the payola investigations). A former trumpet player for local group Rocco and the Saints, Avalon embarked on a successful solo career(1958), under Clark's guidance and promotion. Avalon's biggest hit of the 1960s was "Why" which actually made No. 1 in December 1959. His biggest overall would be the beautiful "Venus" from 1959. (This song was later remade into a 1976 disco version, also by Avalon. My advice is to just listen to the original; it's better.) In the early to mid-60s, he did several hilarious "Beach Party" movies with Annette Funicello.
Fabian Forte was also discovered by Marcucci, who proceeded to give the budding star voice and etiquette lessons for two years, and then tried unsuccessfuly to sell him in the music industry trade papers. Under Dick Clark's promotion in 1959, Fabian became an overnight heart throb. His biggest hit was "Tiger" a no. 3 smash in 1959, but he's best remembered for "Turn Me Loose", which made No. 9, also in 1959. There's a lot of debate as to whether Fabian could actually sing. (I've listened to several of his records, and I'd have to say NO. I DO think that he was a leading example of great marketing strategy.)
Bobby Rydell(born Robert Ridarelli)was a friend of Frankie Avalon's and also a member of Rocco and the Saints. Rydell also started a solo career in 1958, but didn't "break out" until 1959 with "Kissin Time"(and Bandstand promotion). His biggest overall hit was "Wild One"(1960, but the swinging, breezy "Volare"(also 1960), and his last hit, "Forget Him" were both no.4 smashes. Check him out in the 1963 movie version of "Bye Bye Birdie". He was quite good!
The late Ricky Nelson became a HUGE singing star by performing on his parents' TV show "The Adventures Of Ozzie And Harriet". Of his many hits, "Poor Little Fool" and "Travelin' Man" went to No. 1. He also had many double-sided hits through 1964, but the British Invasion knocked him off the charts(as well as other idols)for a few years, but he made a brief comeback with "Garden Party"(1972).