Suggestions by @bladeevans

'Weird Al' Yankovic

as Nice Cream Guy in Undertale

Sally Field

as Snowdrake's Mother in Undertale

Sally Field

as Snowdrake's Mother in UNDERTALE - THE MOVIE - a "harry potter-ish" fantasy movie

Jada Pinkett Smith

as Snowdin Shopkeeper in UNDERTALE - THE MOVIE - a "harry potter-ish" fantasy movie

Alan Rickman

as River Reaper in Undertale

Robert Helpmann

as PAPYRUS in Undertale

Jack Black

as Mettaton in Undertale

Chris Pratt

as Frisk in Undertale

Jack Black

as Nice Cream Guy in Undertale

Jack Black

as Nice Cream Guy in Undertale

Will Geer

as Gerson in Undertale

Tom Kenny

as Flowey the Flower in Undertale

Alex Hirsch

as Flowey the Flower in Undertale

Jada Pinkett Smith

as Snowdin Shopkeeper in Undertale

Awkwafina

as Undyne in Undertale

Toby Fox

as Composer in Undertale

P.J Heywood

as W. D. Gaster in Undertale

Kate Micucci

as Alphys in Undertale

Micheal Giacchino

as Composer in Undertale

Bill Hader

as Mad Dummy in Undertale