Pinched this idea from the former BBC boards

[Antares]

25 movies with a real animal as leading "cast"

1. Free Willy 
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule

[DJ Doena]

25 movies with a real animal as leading "cast"

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven

[Critter]

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie

[DJ Doena]

25 movies with a real animal as leading "cast"

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper

[Critter]

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper
12. Napolean

[Rogmeister]

25 movies with a real animal as leading "cast"

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper
12. Napoleon
13. My Pal Trigger

[Dragonfire]

25 movies with a real animal as leading "cast"

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper
12. Napoleon
13. My Pal Trigger
14. Marmaduke

[kahless]

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper
12. Napoleon
13. My Pal Trigger
14. Marmaduke
15. White Fang

[Mustrum_Ridcully]

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper
12. Napoleon
13. My Pal Trigger
14. Marmaduke
15. White Fang
16. Black Beauty

[kahless]

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper
12. Napoleon
13. My Pal Trigger
14. Marmaduke
15. White Fang
16. Black Beauty
17. The Bear (1988)

[Najemikon]

1. Mr. and Mrs. Smith - Brad Pitt and Angelina Jolie
2. Far and Away - Tom Cruise and Nicole Kidman
3. The Break-Up - Jennifer Aniston and Vince Vaughn (self-fulfilling prophecy btw)
4. Jab We Met - Shahid Kapoor and Kareena Kapoor (not married or related despite the same last name)
5. The Marrying Man - Alec Baldwin and Kim Basinger
6. Hackers - Johnny Lee Miller and Angelina Jolie
7. Pushing Tin - Angelina Jolie and Billy Bob Thornton
8. Scooby Doo 1 & 2 - Freddie Prince jr. and Sarah Michelle Gellar
9. The Long, Long Trailer - Desi Arnaz and Lucille Ball
10. Cruel Intentions - Reese Witherspoon and Ryan Phillippe
11. U, Me aur Hum - Ajay Devgan and Kajol
12. Innerspace - Meg Ryan and Dennis Quaid
13. LolliLove - James Dunn and Jenna Fischer
14. Bugsy - Annette Bening and Warren Beatty
15. Overboard - Kurt Russell and Goldie Hawn
16. Kyun! Ho Gaya Na.../Kuch Naa Kaho  - Abhishek Bachchan and Aishwarya Rai
17. No Man of Her Own--Clark Gable and Carole Lombard
18. Eyes Wide Shut (once again Kidman - Cruise)
19. To Have And Have Not - Humphrey Bogart and Lauren Bacall
20. Adam's Rib - Katherine Hepburn and Spencer Tracy
21. Flesh and Bone - Meg Ryan and Dennis Quaid
22. My Pal Trigger - Roy Rogers and Dale Evans
23. Cleopatra - Richard Burton & Elizabeth Taylor
24. The Postman Always Rings Twice - Jack Nicholson and Anjelica Huston

[Mustrum_Ridcully]

1. Mr. and Mrs. Smith - Brad Pitt and Angelina Jolie
[...]
24. The Postman Always Rings Twice - Jack Nicholson and Anjelica Huston

??
I guess it was a loooong night?


25 movies with a real animal as leading "cast"

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper
12. Napoleon
13. My Pal Trigger
14. Marmaduke
15. White Fang
16. Black Beauty
17. The Bear (1988)
18. Lassie

[kahless]

25 movies with a real animal as leading "cast"

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper
12. Napoleon
13. My Pal Trigger
14. Marmaduke
15. White Fang
16. Black Beauty
17. The Bear (1988)
18. Lassie
19. Two Brothers (2004)

[Najemikon]

??
I guess it was a loooong night?

Bloody hell! I just clicked the "New" button. 

[lyonsden5]

25 movies with a real animal as leading "cast"

1. Free Willy
2. Babe
3. That Darn Cat!
4. Turner & Hooch
5. Benji
6. Gus
7. The Cat From Outer Space
8. Francis the Talking Mule
9. Beethoven
10. Paulie
11. Flipper
12. Napoleon
13. My Pal Trigger
14. Marmaduke
15. White Fang
16. Black Beauty
17. The Bear (1988)
18. Lassie
19. Two Brothers (2004)
20. Homeward Bound: The Incredible Journey