Suggestions by @astorredd

Conan Gray

as Sirius Black in Marauders

Score: +3

Dane DeHaan

as Peter Pettigrew in Marauders

Score: +1

Alex Lawther

as Peter Pettigrew in Marauders

Score: +2

Jamie Campbell Bower

as Xenophilus Lovegood in Marauders

Score: +1

Rose Leslie

as Molly Prewitt in Marauders

Score: +1

Lauren Cohan

as Nymphadora Tonks in Marauders

Score: +1

Adam Driver

as Severus Snape in Marauders

Score: +1

Geraldine Somerville

as Carol Evans in Marauders

Score: +2

Cillian Murphy

as Alphard Black in Marauders

Score: +1

Helena Bonham Carter

as Bellatrix Black in Marauders

Score: +1

Anna Baryshnikov

as Young Pomfrey in Marauders

Score: +1

Hailee Steinfeld

as Young McGonagall in Marauders

Score: +1

Margot Robbie

as Rita Skeeter in Marauders

Score: +1

Zoë Kravitz

as Dorcas Meadowes in Marauders

Score: +1

Arthur Darvill

as Arthur Weasley in Marauders

Score: +1

Freya Mavor

as Narcissa Black in Marauders

Score: +1

Colin Firth

as Orion Black in Marauders

Score: +1

Maggie Smith

as Minerva McGonagall in Marauders

Score: +1

Dakota Fanning

as Ariana Dumbledore in Marauders

Score: 0

Jake Gyllenhaal

as Fleamont Potter in Marauders

Score: -1