Nickel based superalloys with excellent mechanical strength, corrosion resistance and oxidation resistance, which consist essentially of chromium in an amount of 3 to 7% by weight, cobalt in an amount of 3 to 15% by weight, tungsten in an amount of 4.5 to 8% by weight, rhenium in an amount of 3.3 to 6% by weight, tantalum in an amount of 4 to 8% by weight, titanium in an amount of 0.8 to 2% by weight, aluminum in an amount of 4.5 to 6.5% by weight, ruthenium in an amount of 0.1 to 6%, hafnium in an amount of 0.01 to 0.2% by weight, molybdenum in an amount of less than 0.5% by weight, carbon in an amount 0.06% by weight or less, boron in an amount of 0.01% by weight or less, zirconium in an amount of 0.01% by weight or less, oxygen in an amount of 0.005% by weight or less, nitrogen in an amount of 0.005% by weight or less and inevitable impurities and the balance being nickel.