Unforgettable brings the thriller genre into the realm of domestic life and divorce, featuring a woman whose obsession is directed at her ex-husband's new wife. Rosario Dawson plays Julia, who is building a new life with her fiancé David (Geoff Stults) and his daughter. Things take a sinister turn when David's ex-wife, Tessa (Katherine Heigl), enters the picture.

Tessa is seemingly perfect and composed on the surface, but beneath lies a seething jealousy and determination to reclaim her old life by any means necessary. Katherine Heigl steps into a darker role here, portraying the calculating and manipulative Tessa with chilling precision. The film explores themes of envy, control, and the lengths someone will go to destroy another person's happiness. While not about a best friend, it fits the theme of a woman obsessing over another woman in a dangerous way, escalating from psychological mind games to outright threats. It's a suspenseful ride as Julia realizes the full extent of Tessa's obsession and fights back.

Greta offers a fascinating, albeit slightly different, take on female obsession, focusing on the relationship between a young woman and an older stranger. Chloë Grace Moretz plays Frances, who finds a lost handbag on the subway and returns it to its owner, the eccentric piano teacher Greta, played with unsettling brilliance by Isabelle Huppert.

An unlikely friendship forms, initially filling a void for both women. However, Greta's affection quickly turns into a possessive and terrifying obsession. Huppert's performance is the undeniable highlight – she is captivatingly unhinged, shifting from lonely widow to terrifying stalker with chilling ease. The film isn't strictly about a 'best friend' but rather a surrogate maternal figure whose need for connection becomes pathologically dangerous. Directed by Neil Jordan, it builds a palpable sense of dread and features some truly shocking moments. It's a stylish and effectively creepy thriller that showcases the immense talent of its lead actress.

Diving into the perils of shared living spaces, The Perfect Roommate explores what happens when the person you invite into your home turns out to be anything but ideal. This thriller taps into the fear of a seemingly perfect stranger becoming a dangerous intruder in your life.

The premise often involves a protagonist seeking a new roommate, only to find the person who moves in harbors dark secrets and an unhealthy fixation. As the film progresses, the initial pleasantries dissolve, revealing a sinister agenda and escalating threats. These types of thrillers excel at creating a sense of claustrophobia and vulnerability, making you question who you can truly trust. While specific plot details can vary, the core tension lies in the victim being trapped in their own home with someone who is systematically dismantling their life. It's a thrilling concept that preys on common anxieties about privacy and safety, delivering suspense as the protagonist fights to regain control.

The Roommate takes the classic 'Single White Female' premise and updates it for the college campus, delivering a slick and suspenseful ride. Starring Minka Kelly as the sweet, naive Rebecca and Leighton Meester as the increasingly unsettling Sara, the film explores the intense, sometimes suffocating dynamics of dorm life.

When Rebecca arrives at college and is paired with Sara, she initially finds a seemingly kind and eager friend. However, Sara's initial friendliness quickly morphs into a disturbing obsession, as she tries to control Rebecca's life and eliminate anyone she sees as a threat to their bond. Leighton Meester shines in her role, bringing a chilling intensity to the character of Sara. It's a fun, popcorn thriller that capitalizes on the inherent anxieties of moving away from home and trusting strangers. The film effectively builds tension as Rebecca slowly realizes the danger she's in, making it a highly engaging watch for anyone who loves a good psychological stalker story.

If you're looking for the ultimate thriller about a friendship gone terrifyingly wrong, Single White Female is the absolute benchmark. Starring Bridget Fonda as the unsuspecting Allie and Jennifer Jason Leigh as the seemingly perfect roommate Hedy, this film dives deep into psychological horror.

When Allie advertises for a roommate after a breakup, Hedy appears like a godsend – quiet, polite, and seemingly harmless. But as Hedy becomes increasingly obsessed with Allie, mirroring her appearance and behavior, the film escalates into a chilling study of identity theft and dangerous fixation. Jennifer Jason Leigh delivers an absolutely captivating and unnerving performance that is central to the film's enduring power. Directed by Barbet Schroeder, it's a masterclass in building suspense and paranoia, making you question how well you really know the people closest to you. It practically invented the 'roommate from hell' trope and remains incredibly effective decades later. A must-watch for fans of psychological thrillers!