According to cosmology, the first stars in the universe would have been built solely from hydrogen and helium with a trace of lithium, because the primordial nucleosynthesis would only have had enough time to make helium and that lithium trace. Such stars would have been more transparent to radiation than stars containing other elements (which astronomers call metals), and consequently could have been much larger than those that exist in the universe today.
Today's New York Times has a Dennis Overbye story claiming that the signatures of these early monsters have been found in a galaxy seen as it was only a few hundred million years after the big bang.
Astronomers said on Wednesday that they had discovered a lost generation of monster stars that ushered light into the universe after the Big Bang and that jump-started the creation of the elements needed for planets and life before disappearing forever.
Modern-day stars like our sun have a healthy mix of heavy elements, known as metals, but in the aftermath of the Big Bang only hydrogen, helium and small traces of lithium were available to make the first stars.
Details at the link.