George C. Scott in The Day of the Dolphin (1973)

Jake Terrell (Scott) and his wife (Trish Van Devere) are researching dolphin intelligence and their relationship with humans. In the process of their research they've been able to directly communicate with one of them by teaching him English. Unbeknownst to them, there are radical right wing forces bent on destroying the President of the United States. They've learned of Terrell's dolphin and plans to use him and his mate to carry out the job.

Wikipedia

This film is directed by Mike Nichols and the screen play is by Buck Henry, so when I first started watching it I was sort of expecting a comedy - at least I was expecting some satire. Instead, it explores some of the more esoteric ideas about our relationship to other species in the setting of a political thriller. It's marginally successful at both, though tends to have a bit of a split personality.  

This film does not have a high profile, though it is remembered by some. It was nominated for two Academy Awards (score and sound) but has fallen into obscurity over the years. Above is a television commercial for a 1977 airing of it, uploaded to YouTube by robatsea2009

Obscurity factor: 7 (available on DVD, not largely remembered)

Julie Christie in Demon Seed (1977)

Just like Hal 9000 in 2001, this film features a homicidal computer (Proteus IV), but unlike misunderstood Hal, this one is cruel and willful. Susan Harris (Christie) is the wife of Alex (Fritz Weaver), a computer programmer working in the area of artificial intelligence. Because of his total immersion in his work, Susan thinks he's becoming dehumanized and they've decided on a trial separation. Meanwhile, the project Alex is working on - a super computer designed to mimic human reasoning and abstract thought - is starting to become somewhat difficult to handle. Little does Alex know that it's taken over his highly computerized home and is holding his wife captive as it tries to convince her to submit to heinous experiments into the human condition.

MoviePosterShop.com

This disturbing film has has some scary moments in it, and has an extremely bleak outlook on our relationship with technology. It also has some far reaching plot points that tend to bend ones ability to suspend disbelief. The computer is voiced menacingly by Robert Vaughn

This film is available on DVD and is moderately well known, though not a classic by any stretch of the imagination. The trailer is above, uploaded to YouTube by warnerarchive.

Obscurity factor: 6 (somewhat known, on DVD)