The Simpsons
The Simpsons will celebrate their 500th episode

The longest and the most successful animated sitcom of all time, the Simpson, will mark its 500th episode this Sunday after a successful run for 22 years.

Nobody, including creator Matt Groening, expected the show to be so successful for so many years.

"I never imagined this. I thought it would be a hit with kids. I wasn't sure adults would dig it," USA Today quoted Groening as saying.

In spite of furious competitions by other animated sitcoms such as "The Family Guy," "The Jetsons," "The Flintstones," etc; the yellow skinned dysfunctional family has not failed to entertain both adults and children for over two decades.

"In a business where things get tired in a matter of months, we were able to sustain for a whole generation," USA Today quoted Al Jean, executive producer, as saying.

So what is the secret of the undoubted success of this show, airing since 1989?

"I think it's the flexibility of these characters. They can do any kind of comedy anyone ever thought of, from farce to reality," says executive producer James L Brooks, according to USA Today.

But it has not always been a joy ride for the Simpsons cast and crew as just last year Fox network nearly pulled the plug on the show and have always threatened to do so if the show sops stop making them profits.

However, an another two season deal (59 more episodes) has been signed after the show's crew and cast agreed to keep working on a lesser salary to ensure the survival of their beloved show.

The Simpsons is the longest running television show of all time with 500 episodes. Here's a list of the other top 10 Longest Running Television Comedies of all-time:

1. The Adventures Of Ozzie & Harriet, 1952-1966 (435 episodes)

2. My Three Sons, 1960-1972 (380 episodes)

3. The Danny Thomas Show / Make Room For Daddy 1953-1975 (336 episodes)

4.The Donna Reed Show, 1958-1966 (275 episodes)

5. The Beverly Hillbillies, 1962-1971 (274 episodes)

6. Frasier, 1993-2004 (264 episodes)

7. Married ... With Children, 1987-1997 (259 episodes)

8.King Of The Hill, 1997-2010 (257 episodes)

9.M*A*S*H,1972-1983 (256 episodes)

10.Happy Days, 1974-1984 (255 episodes)