Tropical Storm Alpha was the 23rd tropical or subtropical storm of the extremely active 2005 Atlantic hurricane season. It developed from Tropical Depression Twenty-Five in the eastern Caribbean Sea on October 22, 2005. As the 21 pre-designated storm names had been exhausted, it was given the first name on the auxiliary list, which utilized the letters of the Greek alphabet. This was the first hurricane season ever to trigger this naming protocol, and the only one until the 2020 season.

The 2005 Atlantic hurricane season was the most active year on record until surpassed by 2020. It featured 28 tropical or subtropical storms. The United States National Hurricane Center named 27 storms, exhausting the annual pre-designated list, requiring the use of six Greek letter names, and adding an additional unnamed storm during a post-season re-analysis. A record 15 storms attained hurricane status, with maximum sustained winds of at least 74 miles per hour (119 km/h). Of those, a record seven became major hurricanes, rated Category 3 or higher on the Saffir–Simpson scale. Four storms of this season became Category 5 hurricanes, the highest ranking.