Sue Osman is a fictional character from the BBC soap opera EastEnders, played by Sandy Ratcliff. She is one of the serial's original characters, appearing in its first episode on 19 February 1985 and departing on-screen in May 1989. Created by Tony Holland and Julia Smith, Sue is portrayed as argumentative, insecure and tragic. A pivotal storyline in the character's narrative is the cot-death of her son, which was one of the show's first controversial plots. During her four years on-screen, the character contends with a phantom pregnancy, marital breakdown and finally insanity. Ratcliff left the role in 1989.

Sue Osman was one of the original twenty-three characters invented by the creators of EastEnders, Tony Holland and Julia Smith. British Sue and her Turkish Cypriot husband Ali, were an attempt to portray a multi-cultural relationship, with an emphasis on conflicting customs, cultural and personality differences. Their marriage was scripted to be volatile, highlighting the problems that can occur when customs and beliefs are not shared in a relationship.

Sue's original character outline as written by Smith and Holland appeared in an abridged form in their book, EastEnders: The Inside Story.

Sue was the child of older parents. Affection was what was missing from the house. No real love, no fire and no closeness. She never saw her parents touch each other, or demonstrate tenderness ... Is Sue actually looking for a bad time in life? Is she a big martyr? Perhaps convinced that her parents had no affection for her, she can't understand anyone else doing so. She's a very insecure woman — furiously jealous and possessive and always accusing her husband of being unfaithful. She is always putting herself in the position of being the victim. Sometimes she nearly goads her husband into hitting her ... A gigantic, self-imposed, chip on her shoulder... She needs dramas — it's something she is good at. She is a poisonous bitch, but it is important that we understand why.

Holland and Smith required the character of Sue to appear 'hard', but also to be a 'loser' and a 'victim'. They initially considered casting the role of Sue to Gillian Taylforth, the actress who would go on to play Kathy Beale in the serial. In the end she was rejected because she had blonde hair and they had always envisioned Sue to be a brunette. Sandy Ratcliff (previously a model who was cast as Lord Snowdon's face of the seventies) was recommended for the role by the writer Bill Lyons. Ratcliff was invited in for audition. Holland and Smith were struck by her appearance, suggesting she had "one of the most photogenic faces on television". They suggested that she had a "toughness in her face and manner, a fiery gypsy-like quality." and that she sounded "East-end enough". Holland and Smith surmised that Ratcliff would clearly be competent at playing the "hard" aspect to Sue's character, but they were not originally certain that Ratcliff would be able to portray the loser and victim aspects as convincingly because, on the surface, Ratcliff appeared to be the exact opposite.

Ratcliff was renowned for being a staunch feminist and a political actress; Holland and Smith initially feared that her own personality and strongly held views would be at odds with the character. For instance, Ratcliff requested that they make the cafe that Sue was scripted to run into a "women's-only bookshop". Ratcliff was also not renowned for being the most disciplined actress, 'more the free spirit', which sparked fears over how she would react to the strict disciplines of a twice-weekly drama. However, it was eventually decided that Ratcliff did possess all the qualities that were needed to play Sue convincingly and, despite initial objections from Ratcliff's agent who did not approve of her artists appearing in soap operas, she become "hot favourite" for the role. Although auditioning for Sue was done first, the casting could not be confirmed until an actor was found to play her husband, Ali. Ratcliff was brought in at a later date to read scripts with two potential actors, Nejdet Salih and Haluk Bilginer (two out of only three working Turkish speaking actors in London at the time). The creators differed in opinion on which of the two they wanted to have the role; it was initially felt that Ratcliff would "make mincemeat" out of Salih, but following a successful reading, it was eventually decided that Salih and Ratcliff worked as the Osman partnership and were cast as Sue and Ali. Bilginer was cast as Ali's brother Mehmet.

Sue has been described as "highly strung" with a parlous emotional state. Author Hilary Kingsley has suggested that Sue was a character who was "dogged by tragedy". She suggested that Sue was a "moaner" but despite this she "did enjoy life a lot", making reference to her love for her husband Ali (despite his flaws) and her babies as evidence of this. Kingsley's summation of Sue stems around psychological problems however, with her suggesting that Sue was "always mentally unstable" and that she was never "that strong at the best of times". In her book Soapbox, Kingsley suggested that Sue, like many women in EastEnders, was "very much the power behind the throne. She virtually runs the cafe singlehanded. She fights with their [property] landlord, tells the customers (the other residents) the unvarnished truth about themselves and struggles to keep Ali from gambling away the profits."

Before the show aired, Holland and Smith had already decided that Sue and her husband would be parents to a young baby named Hassan. However, as further characters were invented they realised that there would be a total of four babies in the show: Annie Smith, Martin Fowler, Vicki Fowler and Hassan. It was decided that it would be impossible for the studios to cope with four babies, and so they invented a storyline to eliminate one of the young babies from the cast. During this time in the 1980s, the issue of cot death was prominent in the British press, partly due to an increase in casualties, but also because a doctor had gone public with the accusation that parents were to blame for the tragic occurrence. Holland and Smith decided that covering this issue in the soap would be a good way of 'setting the record straight', and so it was decided that Sue and Ali's baby would die from cot death in the early months of the show. This was the first of many controversial storylines in EastEnders' history. After the storyline aired in June 1985, the show was praised by audience and press alike for the sensitive and unsensational way the subject was treated. The sudden tragedy came as a surprise to the audience, especially since the bereaved parents were a couple whose feuding, fighting ways had made them appear rather comic in the early episodes of the show. The British Cot Death Foundation initially feared that a soap opera would trivialise the subject and frighten new parents. They tried to stop the episodes from airing, but in the end they were pleased with the way the subject was handled, and provided back-up support after transmission to many viewers who wanted more information on the subject.