- Main article: January 2010
- Main article: February 2010
- Main article: March 2010
- Main article: August 2010
- Main article: Septmeber 2010
- Main article: Octber 2010
- Main article: December 2010
Beginning of January
- Full moon is shown.
- Mason's transformation; full moon.
- Tyler's first transformation; full moon
- Tyler's second transformation; full moon.
- Klaus breaks the hybrid curse.
- Two days Klaus became a hybrid. The second season ends on this date.
- Elena is looking for clues about Stefan's whereabouts.
- Damon is following the leads, but hiding the information from her.
- Stefan and Klaus are following leads, trying to find a werewolf pack - Klaus wants to start his hybrid army.
- Elena's 18th birthday party occurs.
- Andie dies.
- Klaus, Stefan and Katherine visit Chicago. Rebekah is undaggered. Damon and Elena try to save Stefan from Klaus.
- Klaus tries to create a hybrid; full moon.
- Klaus turns Tyler into a hybrid.
- School starts.
- Klaus is staked.
- Alaric dies.
- The third season ends.
- Elena becomes a vampire.
- April Young, Hayley and a vampire hunter named Connor come to Mystic Falls.
- The Council makes its moves against the known vampires.
- Bonnie's grandmother dies a second time.
- Stefan tries to teach Elena to feed only from animals - it does not work.
- Klaus is back in his body and out of town.
- Rebekah tries to make amends with Elena and Matt, but it goes badly.
- Connor makes his moves: shoots Tyler, poison party beer with Werewolf Venom, sets booby traps. But he gets captured by Damon and Klaus, who has an interest in him because he is one of the Five.
- Klaus is back in town with some hybrids - just in time to save Elena from Werewolf Venom.
- Stefan team up with Klaus to get information from Rebekah, which leads to her being daggered - again.
- Damon gives Elena alternative food sources : blood bag, his own blood. It turns out she can only feed from humans. She feeds on Matt until she looses control, then Damon takes her on a hunting trip on a Frat Party.
- Connor makes Jeremy, Matt and April hostages in the Mystic Grill.
- Tyler, Caroline, Damon and Elena are making plans to kill him, Stefan tries to prevent it (He know Klaus needs the hunter alive to read his tattoos.)
- Klaus finds Alexander's sword in Italy.
- Klaus sends yet another hybrid to rescue the hostages, he gets killed.
- Stefan saves Connor, but he ends up killed by Elena.
- The hunter's mark appear on Jeremy's hand.
- Elena has hallucinations.
- Elena's hallucinations get worst. Mistaking Jeremy for Connor, she stabs him on the neck, killing him.
- Luckily he was wearing the Gilbert Ring, so he came back to life.
- Elena is still mad at Stefan because he is working with Klaus, compelled Jeremy to forget something and has been hiding stuff from her.
- Klaus recovered Alexander's Sword. He kidnaps Elena to keep her safe from her hallucinations.
- Tyler and Hayley are working to free the hybrids from the sire bond. Caroline agrees to fake she is fighting with Tyler to help them.
- Professor Shane gives a lecture about the first immortal, and how his spurned lover buried him alive.
- Damon learns from him that hallucinations will stop when the next hunter is activated.
- Stefan and Caroline tell Klaus about Jeremy being a potential hunter. Klaus agrees to sacrifice one of his few remaining, incredibly precious, impossible-to-make-more-while-Elena-is-a-vampire to activate Jeremy as a hunter.
- The victim was Hayley's friend, who had just broken his sire bond and helped Stefan get to Elena. Poor Chris - we barely knew you...
- Stefan lets Elena escape. Following the hallucinations, she goes to the Wickery Bridge, where she throws away her ring. Damon saves her in the nick of time.
- Stefan and Elena break up.
- Stefan lets Elena escape. Following the hallucinations, she goes to the Wickery Bridge, where she throws away her ring. Damon saves her in the nick of time, just before sunrise.
- Stefan and Elena break up.