Like Infinity and Oblivion (depending on who you ask) The Phoenix was created right in the middle of the Big Bang. At the perfect moment when nothing else existed (except Oblivion), the Phoenix popped up and was like, "what's up, bitches?" The first thing it did was create Galactus, as I had mentioned earlier. X-Men fans probably remember when Phoenix entered the body of Jean Grey. Many people think of that Phoenix when anyone even talks about the Phoenix, but the Phoenix can go into anyone.
That was my favorite saga in the X-Men series. For some reason it really affected me as a kid. Like many fans, I could relate to Wolverine and his love for Jean Grey. Unrequited love, I must add. When she became the Phoenix and he couldn't help her, it was heartbreaking.