Cooper's supporting part in the commercially successful comedy Wedding Crashers (2005) improved his career prospects, but also led to him being typecast as the best friend to the main character in such comedies as Failure to Launch (2006), The Rocker (2008), and He's Just Not That Into You (2009).
Peran pendukung Cooper dalam film komedi sukses secara komersial Wedding Crashers (2005) tak hanya mempengaruhi prospek kariernya, namun juga membuatnya menjadi pemeran khas sebagai sahabat untuk karakter utama seperti dalam film-film komedi Failure to Launch (2006), The Rocker (2008), dan He's Just Not That Into You (2009).