This may just be the funniest movie of all time. Mel Brooks never before (and never again) worked with the tight parameters he did here: gene Wilder actually wrote most of the script, and that plus the use of the old Universal sets and props seem to have kept Borooks's more sophomoric instincts (which have gone overboard in some of his later films) tightly in check. Thus he--and everyone else in the film--is doing their absolutely finest work ever.
From Teri Garr "rolling in ze hay," to Kenneth Mars's inspired Police Inspector, everyone in the entire film seems to be working at their most hysterically hilarious. Special mention must be given to Gene Wilder giving one of his most classic performances of his strangled-fury schtick ever ("Put... the candle... back!!!") and to Peter Boyle, for his very poignant and funny depiction of the Monster.
But standing above all of the end in terms of sheer brilliance is Madeline Kahn, giving what must be the funniest female performace ever on film as Frankenstein's fiancee and the monster's eventual bride. Unlike everyone else in the film, she's not really parodying anyone other than herself; yet nevertheless her depiction of Elizabeth, the wealthy prude who discovers she's a volcano of passion undeneath, is so funny I'm practically crying almost every time I see this film. There's one brief little scene where she's brushing her hair in her boudoir before the Monster steals into her room and kidnaps her, and for absolutely no apparent reason(which makes the scene all the funnier) she's giving vent to a deeply lusty rendition of "The Battle Hymn of the Republic" while brushing out her hair. It is the funniest five seconds in the entire film--and in a film this hilarious that's saying a lot.