"McLaggen makes Grawp look like a gentleman."
--Hermione Granger (HBP15)
Cormac McLaggen was a “large, wiry-haired youth” and member of the Slug Club. He had a famous “Uncle Tiberius” who was a favorite student of Horace Slughorn’s (HBP7). During his seventh year Cormac tried out for Keeper of the Gryffindor Quidditch team, but was beaten out by Ron for the position when Hermione Confunded Cormac during the tryouts (HBP11). Cormac did not accept this defeat gracefully. In fact, he displays the downside of Gryffindor bravery: arrogance and foolhardiness. To wit, he missed Quidditch tryouts during his sixth year after eating a pound of doxy eggs for a bet (HBP11). When he finally did get in a game, he was so busy telling everyone else what to do that he failed at his own job, and gave Harry a cracked skull to boot, losing the match for the team (HBP19).
Among McLaggen’s many undesirable qualities was an impressive lack of tact – within hours of Ron being poisoned, McLaggen accosted Harry about replacing Ron on the Quidditch Team, not even feigning concern (HBP19). He also seemed to expect preferential treatment based on his connections (HBP11), which did not sit well with Harry. Cormac was so reviled by Harry and Ron that Hermione chose to take him as a date to Slughorn’s holiday party, figuring he would annoy Ron the most (HBP15). McLaggen proved to be entirely self-absorbed, bragging to Hermione non-stop about his Quidditch exploits, and at one point tried to corner Hermione under the mistletoe… though Hermione managed to escape snog-free.
McLaggen is, to Harry's chagrin, quite an able Keeper.