1. Ian Somerhalder (Damon Salvatore): Born December 8, 1978, Ian Somerhalder was approximately 32-38 years old during the show's eight seasons.
2. Nina Dobrev (Elena Gilbert/Katherine Pierce): Born January 9, 1989, Nina Dobrev was approximately 21-29 years old during the show's eight seasons.
3. Paul Wesley (Stefan Salvatore): Born July 23, 1982, Paul Wesley was approximately 27-35 years old during the show's eight seasons.
4. Candice King (Caroline Forbes): Born May 13, 1987, Candice King was approximately 22-29 years old during the show's eight seasons.
5. Kat Graham (Bonnie Bennett): Born September 5, 1989, Kat Graham was approximately 20-28 years old during the show's eight seasons.
6. Zach Roerig (Matt Donovan): Born February 22, 1985, Zach Roerig was approximately 24-32 years old during the show's eight seasons.
7. Steven R. McQueen (Jeremy Gilbert): Born July 13, 1988, Steven R. McQueen was approximately 21-29 years old during the show's eight seasons.
8. Michael Trevino (Tyler Lockwood): Born January 25, 1985, Michael Trevino was approximately 26-33 during the show's eight seasons.
These ages represent the actors' ages at the start and end of the series. Throughout the show's eight seasons, their ages progressed accordingly.