Who are the 7 Chiranjeevi's (immortal) in Hindu Mythology

The Puranas, the Ramayana, and the Mahabharatha describe seven long-lived personalities in the Hindu pantheon. 

The chiranjivis are as follows:

• Ashwatthama :  the son of Drona, a great warrior. Drona did many years of severe penance to please lord Shiva in order to obtain a son who possesses the same valiance as of Lord Shiva. Aswatthama is the avatar of one of the eleven Rudras.
  
  

• Bali : also called Maha Bali (his son was Banasur), was the virtuous emperor of the three worlds and grandson of Prahlad who was of Asura descent. During the Vamana avatar, Lord Vishnu blessed him to be a Chiranjivi. Every year on the day of Onam, he descends to earth from the heavens to visit his people, those of the region of Kerala.
  
  

• Hanuman : served Rama. He stands for selflessness, courage, devotion, strength, and righteous conduct.
  
  

• Kripa :  royal guru of the princes in the Mahabharatha.

• Parashurama : 6th avatar of Vishnu, knowledgeable about all astras, sastras and divine weapons. The Kalki Purana writes that he will re emerge at end of time to be the martial guru of Kalki.
  

• Vibhishana : brother of Ravana. Vibhishana surrendered to Rama before his battle with Ravana. Later, he was crowned king of Lanka after Ravana was killed by Rama. He stands for righteousness. Vibhishana is not a true Chiranjivi, as his boon of longevity is to remain on the earth only until the end of the Mahayuga.
  

• Vyasa :  the sage who composed the Mahabharata. He represents erudition and wisdom. He was the son of sage Parashara and grandson of sage Vashishtha. He was born towards the end of Tretayuga, lived to see the complete Dwaparayuga, and also saw the initial phase of Kalyuga.
  

• Other famous immortals or Chiranjivins: Jambavan, Sage Markandeya, Devapi, Maru, Saptarishis, Kak Bhusundi(Sage living in the form of a crow), Muchukunda the son of Mandhata , Banasur(son of King Bali) by Boon of Shiva, and Udal