James Waddell Alexander II (September 19, 1888 – September 23, 1971) was a mathematician and topologist of the pre-World War II era and part of an influential Princeton topology elite, which included Oswald Veblen, Solomon Lefschetz, and others.

His maternal grandfather, James Waddell Alexander, was the president of the Equitable Life Assurance Society.

[2] They would frequently spend time, until 1937, in the Chamonix area of France, where he would also climb mountains and hills.

Alexander was also a noted mountaineer, having succeeded in many major ascents, e.g. in the Swiss Alps and Colorado Rockies.

[2] During World War I, Alexander served with tech staff in the Ordnance Department of the United States Army overseas.