Loudon's performance as the evil orphanage administrator Miss Hannigan in
Annie won her the
Tony Award and the
Drama Desk Award for Outstanding Featured Actress in a Musical in 1977. In the show she introduced the seminal showtunes "Little Girls" and "Easy Street." Of her portrayal,
Clive Barnes wrote, "As the wicked Miss Hannigan, Dorothy Loudon, eyes bulging with envy, face sagging with hatred, is deliciously and deliriously horrid. She never puts a sneer, a leer, or even a scream in the wrong place, and her singing has just the right brassy bounce to it." Loudon later revisited the character of Miss Hannigan in the ill-fated 1990 sequel, ''Annie 2: Miss Hannigan's Revenge'', which closed quickly after a dismal pre-Broadway engagement in Washington D.C. In 1979,
Michael Bennett cast Loudon as Bea Asher, a widow who becomes romantically involved with a mail carrier she meets at the local dance hall, in
Ballroom. She was nominated for the
Tony Award for Best Leading Actress in a Musical and the
Drama Desk Award for Outstanding Actress in a Musical. She performed the number "Fifty Percent" from the musical during that year's Tony Awards ceremony. During her rendition of
George Gershwin's "Vodka" at the 1983 Tony Awards ceremony while resplendent in a blue sequined gown, she ad-libbed "I'm too good for this room. I'm too good for this song...but I'm not too good for this dress!" At the 38th Annual Tony Awards ceremony in 1984, Loudon performed "Broadway Baby" from
Follies. In
The New York Times, John O'Connor said of her performance, "Miss Loudon has developed the art of mugging into something of a hyperactive disease." In 1980, Loudon succeeded
Angela Lansbury as Mrs. Lovett in
Stephen Sondheim's
Sweeney Todd. In reviewing her performance for
The Christian Science Monitor, David Sterritt said, "Her body sways like a reed in the emotional storms of her own scatter-brained creation, and her off-hand manner becomes still more off-handed when the most explosive matters are at stake ... Loudon gives a comic characterization in the most classical tradition." The following year she co-starred with
Katharine Hepburn and
Julia Barr in the play
The West Side Waltz. In 1982 she won the
Sarah Siddons Award for her work in
Chicago theatre. She appeared in the 1983
Jerry Herman revue ''
Jerry's Girls'' and later the same year she played the role of the miserable middle-aged actress Dotty Otley on Broadway in
Michael Frayn's farce
Noises Off. ==Television and film==