The 2005 Lockdown was a professional wrestling pay-per-view (PPV) event produced by the Total Nonstop Action Wrestling (TNA) promotion, which took place on April 24, 2005, at the TNA Impact! Zone in Orlando, Florida. It was the first event under the Lockdown chronology and the fourth event in the 2005 TNA PPV schedule. Eight professional wrestling matches and one pre-show match were featured on the event's card. Every match took place inside a six sided steel structure known as the Six Sides of Steel. As a result, Lockdown was the first-ever all steel cage event held in professional wrestling.

The Impact Zone is the nickname for any one of three sound stages at Universal Studios Florida in Orlando; they received this nickname due to their use by the professional wrestling promotion Total Nonstop Action Wrestling (TNA), who taped their weekly television series Impact! at the complex for much of its first two decades of existence.