Unless there's something I haven't seen (and there's an awful lot of stuff I haven't seen), then...
Dr. Teeth
Zoot
Lips
Sweetums
Thog
Doglion
The Mutations
Digit
Vicki
Seymour
Foo-Foo
J.P. Grosse (he came close, though)
Hilda
Bobo
Nigel (both of them, actually)
Sam the Eagle
Wanda
Marvin Suggs
The Muppaphone
Mean Mama
Timmy Monster
Beauregard (she did threaten him in The Muppets at Walt Disney World)
Dr. Bunsen Honeydew
Pops
Geri and the Atrics
Statler and Waldorf (but she's threatened Statler)
Miss Mousey
Robin
Vicki
Zhondra
Chip
Ubu
the solid foam drummer
Gaffer
Gogalala Jubilee Jugband
Lubbock Lou and His Jughuggers
Beard
Flash
The Talking Houses
The Newsman
Louis Kazagger
Fleet Scribbler
And I'd like to say that she hasn't karate-chopped Janice, Beaker, Pepe, or Mildred, but I'm not too sure of that.