A character's maximum level depends on how many stars it has, Characters with a lower star level have a lower maximum level. The current maximums are as follows:

• 3 stars and below: Max Level 100
• 3 stars +: Max Level 120
• 4 stars: Max Level 140
• 4 stars +: Max Level 160
• 5 stars: Max Level 180
• 5 stars +: Max Level 200
• 6 stars and more: Max Level 240
• Hawkins Heroes: Unlimited Levels

Once your first five characters reach level 240, you will unlock unlimited Hawkins Hero levels. Check out the “What is Hawkins Heroes?” FAQ for more information.