Here they are:
Daisy Duck- Debuted as Donna Duck in Don Donald. Poor Daisy has always been over looked, even though she is Minnie's bestfriend and Donald's girlfriend. (I like Daisy even more than Minnie) In 1999, Disney came out with the saturday mourning cartoon Mouse Works. It was in this cartoon that a real personality and all was maped out for Daisy, and the "Fab Five" became the "Sensational Six". Though I hardly ever see or hear of Daisy outside of this. In 2001, the Mouse Works cartoons, were transfered to a new show House of Mouse, where Mickey and Donald co-own a night club. (Daisy is the receptionist. I personally like the duet Daisy and Mickey sing together, however, in order to be a good friend to Minnie, Diasy fakes breaking a leg to allow Minnie to perform the song with Mickey, thus giving up her big break. Ofcourse Minnie wound up screwing up the song

Clara Cluck- In many of the cartoons that feature Clara Cluck, she is a singer. There was a good cartoon, with her and Donald singing an Oprah.
Horace Horse Collar- Before the times of Goofy and Donald, Horace was Mickey's right hand man. A no nonsense tough guy, you get on his bad side and he will give you a knuckle sandwhich.
Clara-Belle Cow- Possibly around even longer than Horace, it's possible she was in Plan Crazy. Clara-Belle always played the part of Minnie's confidant, someone Minnie could rely on and take compfort in her companionship. I would not compare this to Minnie and Daisy's girlfriend relationship.
There is a really nice cartoon on the Mickey BW dvd, wear Mickey, Minnie, Horace and Clara-Belle are all on a picnic together. It really features Horace and Clara-Belle.
Peter Pig- He is only in one that I am sure about. (Wise Little Hen) Opposite Donald, in his debut. Frankley this is all I need too see of this character.
BW Ostritch- For those of you who don't know what I am talking about, there is an Ostritch in the early BW Mickey shorts. Mickey rides him in Galloping Gaucho, and He also star in Fire Fighters along side Mickey and Horace. A cute chacter, I wouldn't mind seeing him again.