- Hermione: "I’d thought he’d annoy Ron most. I debated for a while about Zacharias Smith, but I thought, on the whole-"
- Harry: "You considered Smith?"
- Hermione: "Yes, I did, and I’m starting to wish I’d chosen him, McLaggen makes Grawp look a gentleman."
- — Hermione speaking to Harry and Luna at the Christmas Party[src]
Arrogant and self-assured, McLaggen illustrates the most negative aspects of the stereotypic Gryffindor characteristics. Though brave, he is more foolhardy than self-sacrificing, and he engaged in childish pranks, such as eating a pound of poisonous Doxy eggs on a bet, to prove his bravery.
Ironically enough, the same dare that led him to eat the doxie eggs also kept McLaggen from joining the Gryffindor Quidditch team, something he cared a great deal about, in his sixth year at Hogwarts. With Oliver Wood's graduation at the end of the 1993-1994 school year and the Triwizard Tournament canceling all Quidditch matches the following year, the Gryffindor team was in need of a Keeper at the beginning of the 1995-1996 school year. Unfortunately for McLaggen, he was in the hospital wing being treated for doxy egg poisoning at the time of tryouts and Ron Weasley was made Keeper instead. The following year, Ron beat him in saves during try-outs. This may have been because Hermione Granger, who overheard McLaggen made rude remarks about Ron and Ginny Weasley, placed the Confundus Charm on him.
When Ron was hospitalized before Gryffindor's second game against Hufflepuff, Harry was forced to play McLaggen as his reserve keeper. In the week leading up to the match Harry had his doubts about his new Keeper, as McLaggen was bossy and a know-it-all who Harry couldn't wait to be rid of. The match was a no-holds-barred disaster as McLaggen spent more time trying to tell the rest of the team how to play rather than watching the rings, resulting in several goals. This culminated in him wrestling the beater's bat away from Jimmy Peakes and attempting to show him how to hit a bludger, only to knock Harry off his broomstick and crack his skull. The fiasco was possibly Gryffindor's worst and most embarassing loss ever and Ron told Harry in the hospital wing that he thought "the rest of the team might've dealt with him before you get out of here, they're not happy..."
McLaggen was also a member of the Slug Club in his seventh year. He attended Horace Slughorn's Christmas party with Hermione Granger, another club member. However, Hermione only asked him to go in an attempt to make Ron Weasley jealous. Instead, McLaggen ended up driving her crazy by talking about himself excessively and being too forward romantically. When Ron asked Harry about the pair, he was "slightly more cheerful" to learn that the date did not go well.
Behind the scenes
- The name Cormac is borne by a number of figures from Irish legend and history, including Cormac mac Airt, a warrior king of Ireland, and Cormac Cond Longas, an exiled prince of Ulster. The name can be translated into "raven"; these birds are strongly associated with warfare in Celtic mythology. This may allude to McLaggen's aggressive personality.
- Cormac McLaggen will be played by Freddie Stroma in the upcoming Harry Potter and the Half-Blood Prince (film).