Here is the full list of all 49 LEGO Harry Potter: Years 5-7 achievements worth 1,000 gamerscore.
Use a Weasley box with every Weasley
Complete the game to 100% (Single Player Only)
Unlock all of the members of Dumbledore's Army (Single Player Only)
Unlock ALL of the Order of the Phoenix character variants (Single Player Only)
Unlock every character with a pet (Single Player Only)
Unlock all witch characters (Single Player Only)
Defeat every Harry freeplay variant as Lord Voldemort
Unlock every bad wizard (Single Player Only)
Complete the Bonus Level
Unlock every pyjama character variant (Single Player Only)
Defeat Bellatrix with Neville (Waiter) in a duel
Defeat Bellatrix as any Sirius Black character variant in a duel
Defeat 30 Red Caps
Complete "The Flaw in the Plan"
Complete Year 8
Complete "Snape's Tears"
Complete "Fiendfyre Frenzy"
Complete "Burning Bridges"
Complete "Back to School"
Complete "The Thief's Downfall"
Complete "DOBBY!"
Complete Year 7
Use a Quibbler dispenser 25 times
Complete "Lovegood's Lunacy"
Complete "Sword and Locket"
Complete "In Grave Danger"
Complete the scene where Hermione and Harry dance in the tent
Visit the Hogwarts Foyer in Year 7
Unlocked on hitting 50% game completion (Single Player Only)
Complete "Magic is Might"
Complete all lessons (Single Player Only)
Complete "The Seven Harrys"
Use the Deluminator
Complete "Horcrux and the Hand"
Complete Year 6
Complete "Felix Felicis"
Complete "Love Hurts"
Complete "A Not So Merry Christmas"
Complete "Just Desserts"
Collect 1 billion studs (Single Player Only)
Complete "Out of Retirement"
Complete "A Veiled Threat"
Complete Year 5
Complete "A Giant Virtuoso"
Complete "Kreacher Discomforts"
Complete "Focus!"
Complete "Dumbledore's Army"
Stand still with no controller input for 5 minutes
Complete "Dark Times"