Don't be frightened off by the 'Grotesque' name, this is Kraków's premier puppet and children's theatre. Organising some of the city's best events (like the amazing annual Dragon Parade), this theatre dates back to 1945 and performs about 450 spectacles a year. Though performances are in Polish, Groteska is a very visual theatre, making the language barrier less of an issue. Check their website for coming performances.
Box office open 08:00 - 14:00, 16:00 - 19:00; Sat 14:00 - 19:00, Sun 2 hours before the performance. Note the theatre takes a summer break until the end of August.