Isn't that a Star Pact?
I can get behind that though, I love those Far Realm friends.
One of my "flavor" complaints about the warlock is that it has such widely divergent sources -- fey, far realms, nine hells -- all granting arcane power. (Of course I understand it from a game design perspective.)
My way of rationalizing this is to say that the beings that warlocks pact with are not giving the warlock their own "personal" power but, rather, are just teaching the warlock arcane secrets that they know. In this view, the Alien power source represents the actual energies of the far realms.