Wilder loves creating characters, and he created many memorable ones in "Young Frankenstein." He says, "I love creating a character in a fantastical situation, like 'Dr. Frankenstein,' like 'Leo Bloom,' a little caterpillar who blossoms into a butterfly. I love that" (Editors). Brooks on the other hand is known for his directing and producing, which brought him and Wilder together. However, when he was younger, Brooks was a TV comedy writer who worked for legend Sid Caesar. Another writer notes, "Brooks was competing to get his gags on the air alongside those from youthful contenders like Neil Simon and Woody Allen. He couldn't just be funny, he had to be funnier than anybody else. It made him fearless to the point of frantic" (Williams 1). Therefore, he was the perfect co-writer for Wilder's screenplay, he had the writing experience and the comedic experience, and the background in producing and directing to bring the screenplay to theaters.

Wilder also gives much of the credit of his acting and screenwriting success to Brooks. The AMC Editors...

Thus, the two seemed destined to work together, but something drove them apart, and it has never really brought them together again. However, their work on "Young Frankenstein" remains one of the most successfully funny parodies of all time. The jokes are timeless, the acting is perfection, and the characters are memorable, even today. It is a timeless film, and that may be one reason Brooks has resurrected it for Broadway, with the grudging acceptance of Wilder.
References

Braiker, Brian. "Young Frankenstein's Memoir." Newsweek.com. 2005. 10 Dec. 2007. 1-5. http://www.newsweek.com/id/48951/page/4

Editors. "Gene Wilder & Mel Brooks: A Meeting of Two Crazy Minds." AMCTV.com. 2007. 10 Dec. 2007. http://blogs.amctv.com/future_of_classic/2007/06/gene-wilder-mel.html

Williams, Mary Elizabeth. "Mel Brooks." Salon.com. 2001. 10 Dec. 2007. 1-2.