By now, most people have come across a celebrity’s page on Facebook. More and more musicians and athletes are taking to Facebook Pages to engage with fans through personal updates and photos, which fans see in their home page streams.

In fact, according to PageData, there are 230 musicians & bands and 41 athletes on Facebook with over 50,000 fans. But which celebrities are eliciting the most responses and reactions from Facebook fans?

According to Facebook, Vin Diesel and Susan Boyle are far and away the most engaging celebs (as measured by the total number of fan comments, likes, and wall posts), with over 700,000 and 400,000 responses during April, followed by Britney Spears and Ashton Kutcher – with over 200,000 responses each.

How? As we profiled last month, Vin Diesel (who now has nearly 4 million fans on Facebook, putting him third to only Barack Obama and Dr. House) has grown his Facebook audience dramatically by posting authentic status updates and photos during recent weeks. Fans have always loved this kind of information from celebrities they follow, and Facebook provides a powerful way for them to share easily.

Here are the 15 most engaging celebrities on Facebook, as measured by the number of fan comments, likes, and wall posts for April 2009:

1. Vin Diesel – 737,000
2. Susan Boyle – 412,000
3. Britney Spears – 212,000
4. Ashton Kutcher – 202,000
5. Lady Gaga – 198,000
6. Ashley Tisdale – 87,000
7. Green Day – 179,000
8. Barack Obama 156,000
9. Depeche Mode – 142,000
10. Jonas Brothers – 133,000
11. Linkin Park – 127,000
12. Coldplay – 113,000
13. Bon Jovi – 103,000
14. AC/DC – 102,000
15. Roger Federer – 101,000