Helen

Helen is the central villain of the sci-fi 1998 film, Dream House - she is one of the most advanced super-computers in the world, built by an obsessive father who dreams of having Helen be his ticket to fame and recognition, however in his zeal for perfection he foolishly progammed Helen to be able to overrule his own commands if he ever "wavered" from his orders (thus allowing Helen to break a key Law of Robotics).

Helen would prove to be a deadly and merciless opponent as her A.I. became more corrupt and ultimately began to mimic human madness - putting the family she was designed to care for under the tyranny of a murderous machine that began to see herself as "God".

Trivia

 * she is similar to Hal (who arguably stands as the iconic for rogue computers), she is also the inspiration for a Simpsons Tree House of Horror segment that parodied the plot of Dream House (however the computer in the parody was male and obsessed over Marge)