Mantis is a sweet and hilarious presence. She is the Guardian's conscience and their ultimate cheerleader. In Volume 3, her endearing character becomes more confident in her skin.
Nebula has the best character arc in the Marvel Cinematic Universe. She goes from a dangerous and traumatising living weapon to a loving and supporting leader.
Chris Pratt as Peter Jason Quill, also known as Star-Lord, is the glue that holds the Guardians of the Galaxy together. His journey from part one to three progresses perfectly parallel to the storyline.
Dave Bautista's Drax is one of the most likeable characters in the series. His hilarious dynamic with Quill and Mantis and unique way of perceiving things makes him one of the best characters in the Guardians of the Galaxy.
Groot has always been the scene-stealer in the Guardians of the Galaxy. No matter his size, Groot is a loveable and hilarious presence.
Gamora's character has been through ups and downs throughout the franchise. However, Zoe Saldana has adapted all her versions perfectly.
Cosmo, the Space dog, made her official debut in the Holiday Special. She has a small but meaningful role in the team.
Kraglin is a supporting character but a valuable member of the Guardians. Although, he skips most of the action by staying on Knowhere with Cosmo.