Þröstur is an Icelandic language masculine given name. Notable people with the name include:
- Þröstur Leó Gunnarsson (born 1961), Icelandic actor
- Þröstur Johannesson (born 1955), Icelandic cross-country skier
- Þröstur Þórhallsson (born 1969), Icelandic chess grandmaster