Alexander Doom (pronounced [aːlɛkˈsɑndər ˈdoːm]; born 25 April 1997) is a Belgian sprinter specializing in the 400 metres.

As part of Belgium's relay squad, Doom won a bronze medal, taking third behind the United States and Jamaica in a time of 2:58.72.

The next month, at the European Athletics Championships in Munich, Doom won a silver medal as part of Belgium's 4 × 400 metres relay team.

At the 2024 Summer Olympics in Paris, France, Doom, having skipped the heats, started off the Belgian team in the final that finished 4th in the Mixed 4 × 400 metres relay.

[9] Having qualified for the men's 400 metres semi-final, Doom, suffering from pubalgia, was forced to pull up in the last bend and did not finish the race.