Colin Doyle is Max's older brother, who is the secondary antagonist (as well as anti-hero) in all of the Mostly Ghostly films.
Colin is very tall and muscular. Like his brother, he has brown hair but instead has matching brown eyes.
Colin is very mean and rude to Max, his younger brother, throughout the film. He often teases him, though this could be because of his secret jealously of Max's smarts and girlfriend. He is also grumpy, grouchy, and arrogant.
Max Doyle (younger brother)
Max is Colin's younger brother. However, despite being family, they argue, like most siblings and Colin constantly teases Max throughout the movies.
- Colin is similar to that of Chad from Descendants, who is also portrayed by Jedidiah Goodacre. They are both mean to the protagonists and don't believe in something the main character (Ben in Descendant/Max in Mostly Ghostly) believes in.