Who wrote the Iliad?

The literary tradition names Homer as the author of both the Iliad and Odyssey; however, modern scholarship debates whether Homer actually existed. We have no concrete information about him, only speculation. It seems clear, however, that the ancient Greeks believed that a blind bard named Homer lived sometime around the 8th century BCE and told of the tales of the great Trojan War.

Also, many scholars agree that an entirely different poet wrote the Odyssey. The linear structure of the Odyssey is completely different, as it goes back and forth in time. Even more noteworthy is that our hero Achilles from the Iliad seems to have done a complete 180 between these two works. In the Iliad Achilles is on a quest for glory. He is after it at any cost. Acheiving glory becomes more important than his own life. When we meet up with Achilles in the Odyssey he says that he made a mistake and he would rather be a nobody on earth than a legend in the underworld. These striking differences has lead scholars to question the authorship of the two poems.

Anyways, there is a long winded answer to your question. Homer is the traditional author of both the Iliad and the Odyssey.