Sarah Monohan (Marisol Nichols)

Sarah Monohan is a fictional character from Marvel Comics Spider-Man 4 played by Marisol Nichols played the character in the fourth and fifth of Sam Raimi's Spider-Man films between 2011 and 2014. In the aforementioned films the character's "Slender Man" persona is not portrayed.

Spider-Man 4
Months later Peter turns to Monohan to analyze the substance of the parasitic Carnage and after analysis, Monohan informs him that it makes people more aggressive and that it has a particular liking for him. He was also seen carrying out research on animal subgects, hinting at his future mutation into The Slender Man.

Spider-Man: Rise of the Revolutions
While scripting Spider-Man 5 Raimi expressed interest in portraying Monohan transformation into his villainous alter-ego, the Slender Man. Both actor Marisol Nichols and producer Grant Curtis were also enthusiastic about the idea. However Spider-Man 5 was eventually scrapped and the film takes with 2014's Spider-Man: Rise of the Revolutions which, ironically, had Slender Man Constantine Sekeris' concept art was released on the internet showing what Nichols character would have looked like had the fifth film went ahead.

Spider-Man: The Justice Awakening
Peter sees a vision of Sarah Monohan, reminding Peter to leave Selene out of danger