This study investigates financial contagion and systemic risk transmission among global equity markets using an integrated econometric framework combining Network Vector Autoregression (Network VAR), Time-Varying Parameter VAR (TVP-VAR), and Quantile VAR (QVAR) models. The methodology allows the analysis of interconnectedness, time-varying spillovers, and tail-risk contagion across financial markets. Using representative global indices including the S&P 500, EURO STOXX 50, Nikkei 225, and MSCI Emerging Markets, we estimate dynamic spillover networks and quantile-specific transmission mechanisms. The results indicate that global financial markets exhibit strong interconnectedness, with developed markets acting as dominant transmitters of shocks while emerging markets primarily absorb volatility spillovers. The TVP-VAR results reveal that contagion intensifies significantly during financial crises, while the Quantile VAR results show that spillovers are strongest in the lower tail of the return distribution. These findings highlight the importance of monitoring dynamic financial networks to assess systemic risk and improve financial stability policies.