TDG may refer to:
- Companies
- TDG (company), (ex-Transport Development Group) a British logistics and distribution company
- Traffic Design Group, a New Zealand transport consultancy
- TransDigm Group's NYSE ticker symbol
- Music
- The Depreciation Guild, an indie rock band influenced by video game music
- Thessalonian Dope Gods, an American hard-rock band
- Three Days Grace, a Canadian rock band
- Other
- Thymine-DNA glycosylase, an enzyme