Over the past few years, cryptocurrencies have experienced rapid growth and have become an important component of the global financial system. Digital assets like Bitcoin, Ether, Tether, XRP, and BNB have become highly popular that investors and researchers have started studying their correlation with the traditional stock markets. This research examines the effect of selected cryptocurrencies on the major global stock market indices in India, the United States, Europe, South Korea, Japan, and Canada in the years 2021-2025 using secondary data. Various statistical tools were used such as Augmented Dickey-Fuller (ADF) test, Jarque-Bera test, correlation analysis, volatility analysis, Compound Annual Growth Rate (CAGR), t-test and regression analysis were used to analyze the relationship between cryptocurrency and stock market return. The results show that the original price series of both cryptocurrencies and stock market indices were non-stationary, however, after transforming them into a return series, the data became stationary and suitable for further analysis. The results show that the returns of cryptocurrencies are far more volatile and less normally distributed than the returns of stock markets, and this reflects the riskier and more speculative nature of their returns. While strong relationships were found within the cryptocurrency market, and within stock markets individually, the relationship between cryptocurrency returns and stock market returns was found to be weak. Regression analysis further shows that the influence of cryptocurrencies on the stock market returns is very limited in most regions. Overall, the findings show that cryptocurrencies have a relatively stronger impact on global stock markets in developed economies such as the United States, Europe and Canada whereas the impact is comparatively weaker in developing countries such as India, South Korea and Japan.