Stanley Kowalski is a fictional character in Tennessee Williams' play A Streetcar Named Desire.

Stanley lives in the working-class Faubourg Marigny neighborhood of New Orleans with his wife, Stella (née DuBois), and is employed as a factory parts salesman. He was an Army engineer in World War II, having served as a Master Sergeant. He is a controlling, hard-edged man, with no discernible capacity for empathy, forgiveness, or patience, and no apparent family ties of his own, although he once mentions a cousin. He also has a vicious temper and fights with his wife, sometimes leading to instances of domestic violence, which mirror those of the older married couple who live upstairs, the Hubbells. Near the beginning of the play, Stanley announces that Stella is pregnant.

Stanley's life becomes more complicated when Stella's sister Blanche shows up at their door for a seemingly indefinite "visit". He resents the genteel Blanche, who derides him as an "ape", and calls him a "Polack". She flirts with him but attempts behind his back to get Stella to leave the marriage, intensifying his resentment. She poses a threat; in his mind to both his regimented, hedonistic lifestyle and his marriage and concomitant control of his wife. He determines to eliminate this perceived threat and take his revenge.

Stanley starts asking questions from a seedy street merchant, Shaw, who knew Blanche in her old life. Stanley already knows Blanche is staying with the Kowalskis because she is homeless; her family's ancestral mansion, Belle Reve, has been mortgaged. He learns from Shaw that she was paid to leave Mississippi to quell gossip about her many affairs, which she began after her husband, a closeted homosexual, committed suicide. Overjoyed to have the upper hand, Stanley tells Mitch about Blanche's past, which causes Mitch to end the budding relationship which would have seen Blanche leave the Kowalski household and marry Mitch and replace his dying mother as the object of his love. Stanley's cruelty infuriates the hapless Stella.

That night, Stella goes to the hospital to give birth. Stanley goes out and gets drunk in celebration, and returns home. He finds a similarly drunk Blanche, lost in fantasies of soon-to-be happy times, benefit of Shep Huntleigh.

Mitch, possibly emboldened himself with some liquor, had earlier visited after Stanley and Stella left, and told Blanche that she was not good enough to meet his mother but demanded some sexual attention as that is all she is apparently good for. She told him to get out or she'd scream fire, and he left.

Stanley drunkenly fondles Blanche, who rejects him and affects in high dudgeon. He traps her in the bedroom and easily disarms her after she breaks a bottle to use as a weapon. She collapses and the scene ends with her impending rape. This final assault on what she had left of her dignity sends Blanche over the edge into a nervous breakdown. Blanche tells Stella but Stanley lies to his wife and denies Blanche's claim. Weeks later, Stella has Blanche committed to a mental institution at Stanley's insistence.

In the original play, Stella refuses to allow herself to believe Blanche (with the support of Eunice Hubbell) and stays with Stanley, although she seems to need to convince herself. In the 1951 film adaptation, however, due to the demands of the censors, Stella leaves him and takes their child. Most later film and television versions restore the original ending.