Seamus Finnigan

Seamus Finnigan is a Gryffindor student in Harry's year who is described as having sandy hair. He is a huge Quidditch fan and supports the Kenmare Kestrels, and is best friends with housemate Dean Thomas. His mother is a witch and his father a Muggle, who only found out his wife's secret after their marriage; according to Seamus, it was "a bit of a nasty shock for him when he found out."
Seamus is seen in Goblet of Fire with his mother and Dean attending the Quidditch World Cup. In his fourth year, he attends the Yule Ball with Lavender, and also helps round up the Blast-Ended Skrewts after they run amok during Hagrid's Care of Magical Creatures class. The next year, Seamus is initially influenced by the Ministry's smear campaign against Harry, and his mother nearly prevents him from returning to Hogwarts. He engages in a heated argument with Harry on the first night of the new term over the Daily Prophet's allegations that Harry had merely fabricated the story in a bid for further attention, but he later realises his mistake, offers his apologies to Harry, and becomes a late addition of the D.A. In Half-Blood Prince, Seamus refuses to allow his mother to take him home before Dumbledore's funeral.
Seamus is first mentioned near the climax of Deathly Hallows as one of many D.A. members sheltered in the Room of Requirement during Snape's reign as Hogwarts headmaster when Harry, Ron, Hermione, and Dean return before the Battle of Hogwarts. He enthusiastically greets Dean at the entrance, yet his face is bruised so badly after being punished by the Carrows that Harry initially fails to recognize him until he speaks. During the battle, he, Luna, and Ernie aid Harry in his fight with the Dementors by conjuring their Patronuses (Seamus's takes the form of a fox). He is last seen entering the Great Hall to take part in the final stage of the battle, when Harry shields him and Hannah Abbott from one of Voldemort's curses.
Devon Murray has played Seamus in all of the Harry Potter films to date.