Susan Ida Barlow (previously Baldwin) was the daughter of Ken and Valerie Barlow, twin sister of Peter, ex-wife of Mike Baldwin and mother of Adam Barlow. Her middle name, Ida, is in honour of her paternal grandmother Ida Barlow, who died in 1961.
Susan and Peter were born in 1965. They were raised by Ken and Val in Weatherfield until Val's death in 1971, after which Ken sent the twins to live with Val's parents Alfred and Edith Tatlock in Glasgow (in Scotland), with the intention that they would return to Weatherfield when he had married again. Ultimately, Susan and Peter only paid fleeting visits to Weatherfield before they turned sixteen.
In 1981, Mike Baldwin helped Susan get a job in London. She eventually moved to Newcastle, but returned to Weatherfield in 1985 with the intention of staying. Susan started a relationship with Mike, despite him being more than twenty years older than her and Ken disapproving because of his own hatred of Mike. They got married after a short romance, but in 1987 they separated when Mike pressured Susan into having a baby, even though she wanted to put her career first. When she told Mike that she'd had an abortion, he ended the marriage and they were divorced soon after.
Susan returned to Scotland and gave birth to Adam, and kept his existence secret from Mike and her family until 2001. When Mike found out about Adam and demanded custody, Susan left Glasgow with the intention of going where Mike couldn't find her, but she was killed in a car crash on the journey. 13-year-old Adam survived and many years later returned to his mother's home town.
1965-1985: Early years
Susan and Peter had relatively uneventful childhoods for their first few years, although in 1965, they almost died in a house fire, because a piece of coal fell out of the fireplace and burst into flames. Ken was out at the Rovers getting cigarettes and Valerie was furious. When Valerie was tragically killed in 1971 after being electrocuted, Ken couldn't cope so sent the Susan and Peter to live with their maternal grandparents in Scotland. Although Ken often considered taking the twins back, he always found a reason to keep his distance, so Susan and Peter essentially grew up without a father.
1986-1988: Marriage to Mike Baldwin
In spite of Ken not being there for her when Susan was a child, the adult Susan tried to build a bond with Ken. By 1985, Susan had moved to Newcastle. Following an argument with her mother, Deirdre, Tracy Barlow ran away from home planning to see Susan. When Susan returned to Weatherfield with Tracy, she became interested in her father's business, the Weatherfield Recorder, and began helping him out. Susan liked Weatherfield and the Recorder and told Ken and Deirdre she wanted to stay. They suggested she go home and think about whether such a big change was something she really wanted. Before long she was back in Weatherfield, moving in with Ken, Deirdre, and Tracy. Going out with Ken's arch enemy, Mike Baldwin, created a rift between Ken and Susan. Ken was extremely unhappy when he learned Mike had asked Susan to marry him and insisted she wasn't to see him. At that point Susan moved in with Mike. When she asked Ken to walk her down the aisle he refused to even attend the wedding. He relented, saying that if Susan would move back in with the family, he'd walk her down the aisle. Peter told him he should go, since he had never been there for the children. Ken ran to the wedding and gave Susan away.
In 1987 Susan ended up pregnant to Mike. However, she didn't want to have the baby as she wasn't ready to give up her career prospects to become a mother. So she went to have her pregnancy terminated while claiming she was visiting her friend Cheryl, but Mike saw right through her and knew she'd had an abortion. She later left Weatherfield once again. However, she never had an abortion and gave birth to son Adam on 3rd May 1988, but never told her father Ken.
Many years later in 2001, Ken discovered Susan's secret after son Peter let it slip during an argument that Susan never aborted Mike's baby. Ken went to Glasgow to visit her, but she begged Ken not to tell anyone. Ken let it slip to Deirdre, however, who in turn told her ex-lover Dev Alahan, who informed Mike. Mike was angry and demanded that he wanted to see Adam. Susan decided to up sticks once again, but when trying to escape with Adam, she ended up in a car crash and was killed. Adam however managed to survive the crash. Susan was buried next to her mother Valerie. During the funeral Adam got emotionally exhausted, punched Mike and did a runner.
- Susan made her first appearance in 1965 when she was born with her twin brother Peter to long-term characters Ken and Valerie Barlow. Susan was originally played by Katie Heanue from April 1965 until early 1970 with Heanue's twin brother Robert appearing as Peter during this time. The Heanue twins left their respective roles when they moved away from Greater Manchester. Despite having a stint of nearly five years, the twins were never credited in their roles.
- Following Heanue's departure, the second actress to appear as Susan was Wendy Jane Walker, who was the first credited actor in the role. Walker made her first appearance in April 1970 and played the role until April 1971 when Susan and Peter were written out after their on-screen mother's death. Within the show's continuity, the twins were said to have moved to Scotland. Walker briefly reprised the role on a number of occasions, specifically in September 1971, October 1973 and March 1974.
- Susan made a number of brief returns in December 1979, January and April 1980 and July 1981, the latter appearances as part of a storyline involving on-screen father Ken marrying Deirdre Langton. Susan was played by Suzy Paterson in these appearances.
- Susan returned as a regular character in October 1985 with Wendy Jane Walker taking back the role from Paterson. This stint involved Susan marrying Ken's rival Mike Baldwin. Walker left the role in November 1987 after a storyline where Susan aborted Mike's child.
- Susan returned thirteen years later in early 2001 with the fourth and final actress Joanna Foster playing the role. Susan's final stint saw her introduce her secret son Adam, before her death in a car accident in February 2001.
- Susan not aborting Adam (as revealed in 2001) is somewhat of a retcon in the series continuity. Susan did not "pretend" to abort Adam to escape Mike, she aborted her child as she wasn't yet prepared to have children yet. Also despite Ken only finding out in 2001 that he had a grandson and it is spoken like he hasn't seen Susan since her departure in 1987, he did in fact visit her off-screen in that time.
- Susan's death was revisited sixteen years later in late 2017, as part of a storyline involving Billy Mayhew. In the story, it was revealed that Billy was in a getaway car that forced Susan's car off the road when it sped away from an attempted robbery at a petrol station. The revelation of this broadcast in December that year when Billy (believing he was going to die after a stabbing) revealed the truth to Susan's twin brother Peter Barlow.
First and last lines
"Oh come on Adam, we haven't got time... I've told you!" (Final line)