A Hallmark holiday is a disparaging term used to describe a holiday that exists primarily for commercial purposes, rather than to commemorate a truly significant religious or secular event. The name comes from Hallmark cards, a company that presumably benefits from such manufactured events. In reality, however, there are no Hallmark-created holidays. The only time Hallmark creates cards for a new holiday is when there are enough requests from consumers that it is economically viable to offer the new holiday products.

Examples of holidays denounced as "Hallmark Holidays" include Secretary's Day, Mother's Day, Father's Day, and Sweetest Day. Valentine's Day is likewise often cited as a holiday that has been co-opted by commercial interests to the point where it has been reduced in status to a "Hallmark Holiday," though it does have a longer historic legacy than most.

This phenomenon may be even more common in Japan and South Korea than it is in North America and Europe.

List of alleged Hallmark holidays

• Father's Day
• Halloween
• Mother's Day
• Sweetest Day
• Valentine's Day
• Boss's Day
• Administrative Professionals' Day (also known as Secretary's Day)

Humorous observances