No one created this universe; the universe is the existence with no beginning and no end, with infinite space-time.
"The God who created the world." -- Buddhists have a problem with this because we view the world as part of a larger cosmos that is at least as big as that taught by modern science, and in addition we believe that this universe includes realms that transcend the physical universe. Furthermore, this universe is believed to arise and fall in accordance with causes and conditions in a rhythmic process that takes billions of years to go through just one cycle. This is similar to the modern scientific idea of a big bang and then a big crunch, except that Buddhism teaches that the universe expands and contracts repeatedly over countless eons. The Buddha also taught that we should not concern ourselves with speculations concerning the ultimate beginning or end of this process (assuming that this process is not beginningless and endless) but rather we should focus on taking responsibility for our lives and strive to extinguish suffering by living a noble life characterized by such qualities as loving-kindness, compassion, joy, peace, generosity, virtue, and patience to name a few. To engage in fruitless cosmological speculations instead of working on the practical issue of suffering and the liberation from suffering would be like getting shot and while bleeding to death refusing to go to the hospital for treatment until you knew who shot you, why they shot you, what kind of gun they used, what kind of bullet etc... So, the priority should be on resolving our actual human condition and not speculating on the beginning or end of the universe. So from this perspective, whether God created the universe or not, we are still faced with suffering and its causes and we must do something about it through learning what constitutes a noble life and then finding a way to live such a life.
Aside from the priority of dealing with actual issues versus cosmological speculation, Buddhism also teaches that all things arise and cease depending on causes and conditions. When we say that everything is "empty," we do not mean that things do not exist. What we mean is that things are always elements in a process of change and interdependence. When we learn to see things as processes and not as isolated finite objects then we will see that to talk of something being "created" or "destroyed" is only true conventionally. The network of causes and conditions that bring any "thing" into existence is actually a never-ending process with no boundaries. So in this sense, Buddhism never speaks of "creation" or "destruction," "birth" or "death," "appearance" or "disappearance," because that way of talking about things misses the infinite open-endedness and inclusivity of the process which is the reality behind the "things" that we perceive and try to grasp. This holds true for chairs, people, planets, or universes. This is the other reason why Buddhism does not speak of a creation or a Creator, because the reality of life, the universe, and everything defies such concepts.
There is also the inherent contradiction in insisting that there must be a God who caused the universe because everything must have a cause, but then insisting that God is an exception to the rule that everything must have a cause. Either one must insist that everything has a cause, including God, or one must admit that things do not always need causes and therefore you can not insist that the world or the universe must have a cause. This logical dilemma is another reason why Buddhism does not speak of a creation or a Creator.