Vishala, Visala, Vaisala or Vishal (Sanskrit: viśāla) was a king of ancient India, son of Ikshwaku queen Alambusha. Vaishali is supposed to have got its name from King Vishal, who ruled on this land. It was named Vishalapuri after the king. With time the name changed to Vaishali.
The name of King Vishal is also mentioned in one of the Puranas as well as the Mahabharata.
References
King Vishal Wikipedia(Text) CC BY-SA