Soap breakout characters.

[CAEF]

Characters who started off as just supporting/guest or "Not much happened with them" who later became major characters.

One example is Ian Beale. From 1985 to 1988 he was just skulking around the square with Kelvin, getting into a few odd scrapes and wanting to be a caterer. After Den left in Feb 1989, I guess the writers wanted to build up the remaining original characters to keep the Beale/Fowler family going so Ian was elevated to major character status, especially as he was now in his late teens/early 20s.

JR Ewing in Dallas was originally a supporting character in the 1978 season, and Sue Ellen was, but he became a major character by series 2.

Sally Fletcher in H&A, from 1988 to about 1992 she was just a supporting character but she soon was "JR Ewinged and Ian Bealed" and elevated to major character status.

Jack and Vera in Corrie, originally guest characters who were also elevated to main character status by 1983.

Fred Elliott in Corrie, just a pal of Alf who was a butcher and liked to give bribes out, was made a major character by 1996/1997.

[holey]

Suranne Jones as Karen who began as a mere extra in the factory as a friend of Linda Baldwin.

[CAEF]

Seth Armstrong.

[Nathan]

Bet Lynch originally appeared as a factory worker for a couple of months in 1966, would later return in 1970 and be a major character for the next 25 years at the Rovers Return.

Gail was originally brought in as a friend to already established character Tricia Hopkins, and only appeared in 10 episodes in 1974. She would return permanently in 1975.

[holey]

Although not breakout characters Eastenders have some wonderful Extra's (supporting artists):-

Tracey
Shrimpy
Winston

[butterball]

Not a soap but Tamzin Outhwaite played the killer in an episode of New Tricks, only to become the new Guv'nor later in the series.

[CAEF]

Of course the Dingles in Emmerdale, and Toadie in Neighbours.

[Nathan]

I think Tony Gordon was quite the breakout character despite being a villain who had Liam Connor killed. I remember reading forums and Youtube comments where people wished the character would remain on despite what he had done. He was popular enough for the production team to extend Gray O'Brien's contract to give him an explosive exit, as Tony was originally intended to be locked up and never seen again.

Jed Stone seemed quite popular as he was intended to be a one-off character (and a villainous one at that), but returned full-time in September 1961 as a lovable rogue type figure. He was intended to leave properly in 1963, but brought back throughout 1966 due to fan demand. Unfortunately his 2008 stint didn't do him much favours as he was depicted as a heavy drinker who was meant to get murdered by Tony Gordon on Christmas Eve, which I think put Kenneth Cope off making further appearances.