Desperate Housewives – Bree & Edie
Nicollette Sheridan had originally auditioned for the role of Bree but was cast as Edie Britt instead.
Also, Dana Delany turned down the role three times even though she would later join the series in its fourth season as Katherine Mayfair, a character very similar to that of Bree.
Bree Hodge/Van de Kamp was finally played by Marcia Cross.
Friends – Rachel & Monica
Courteney Cox was originally cast as Rachel but apparently she insisted on being cast as Monica, so Jennifer Aniston ended up playing Ross’s eternal love.
Fun fact: Monica and Joey were going to be the main romance story in the show. Aniston would “end up” with Joey anyway as Rachel, at least for a short while.
Buffy, the Vampire Slayer – Buffy & Cordelia
Other actresses such as Selma Blair and Katie Holmes almost got to play Buffy but Sarah Michelle Gellar finally won the part.
However, Gellar had originally auditioned to play Cordelia; it was the producers who thought she would be better as the leading character.
At that time, she was also up for the part of Sabrina in Sabrina, the Teenage Witch, which ended up being played by Melissa Joan Hart.