Ashwatthaamaa was the son of Guru Dronaachaarya and Kripee (sister of Kul Guru Kripaachaarya). He was immortal and had a gem stone studded on his forehead. His early childhood passed in a very poor condition as his father didn't get any work.

Once he was very hungry, Drone saw Kripee giving him flour mixed water instead of milk. He felt very bad and went to his old time friend Drupad to ask for only one cow for his son. But he refused to give it. Drone wandered around for some time until he met Kaurav and Paandav children making efforts to take out their ball from a well. He came home only when he had got one cow from Drupad. 

Ashwatthaamaa was very mighty and skilled in warfare. He fought very bravely in Mahaabhaarat war from Duryodhn's side.

When the war ended and only Duryodhan remained alive. Bheem had broken his thigh and he was lying on the bank of the pond. Ashwatthaamaa looked for him everywhere, but he couldn't find him anywhere. At last he came at the pond and found him there lying half dead. He asked Duryodhan - "Friend, You are in a very bad condition. Who has done this to you?" Duryodhan said - "Bheem has done this to me." Ashwatthaamaa asked - "Friend, What can I do for you now? I can do anything for you, just tell me." Duryodhan said - "If you can do anything for me, just bring five Paandav's heads." Ashwatthaamaa said - "I will. Just wait for me, don't go away." and he went away immediately.

He came to Paandav's camp. Everybody was sleeping. First he killed Drishtdyumn, the killer of his father. He looked for Paandav's tent. He found one tent where Draupadee's five sons were sleeping. They looked like their fathers, so as he saw them he thought that they were the Paandav. He immediately cut their heads and came back to Duryodhan to give him this good news but unfortunately Duryodhan had already died then.

As soon as Paandav knew about their sons' killing, Arjun said - "I know who has killed them. It is AAshwatthaamaa only. Then he promised to Draupadee that he would bring Ashwatthaamaa to her feet from any corner of the world and put him on her feet. Then she can treat him as she likes." And he went out in search of Ashwatthaamaa along with Krishn.

Seeing Arjun coming behind him Ashwatthaamaa ran all around but Arjun never stopped following him. At last Ashwatthaamaa hid in a Muni's Aashram. There both fought for some time, then Ashwatthaamaa used Brahm Astra on Arjun. Arjun also countered it with Brahm Astra. Now both Brahm Astra proceeded towards each other. Then Brahmaa Jee calmed down both and asked them to return Brahm Astra back. Surprisingly enough Ashwatthaamaa knew how to use it but he didn't know how to return it, so Arjun got his Astra back, but Ashwatthaamaa couldn't get it back. Rather he directed it towards Uttaraa's womb where Pareekshit was growing, with the idea to destroy Paandav's Vansh.

So Ashwatthaamaa lost the battle with Arjun. On advice of Krishn Arjun took out his gem studded in his forehead and brought him to Draupadee for her to decide about his punishment. Draupadee freed him without any punishment saying "First he is your Guru's son, second he is Braahman and she does not want any Brahm Hatyaa Paap, third by killing him her children are not coming back alive.

But Ashwatthaamaa's Astra entered the womb of Uttaraa and burned the fetus. Uttaraa ran towards Krishn for help. Krishn said - "If I have always spoken truth and fulfilled my promises then this fetus should get alive." And the fetus got alive. Later he was born as Pareekshit.

Ashwatthaamaa killed Shikhandee and Dhrishtdyumn also along with Paandav's sons.