The Great Bell of Dhammazedi (Burmese: ဓမ္မစေတီခေါင်းလောင်းကြီး [dəma̰zèdì kʰáʊɰ̃láʊɰ̃ dʑí]) was a bronze bell, believed to be the largest bell ever cast. It was cast on 5 February 1484 by order of King Dhammazedi of Hanthawaddy Pegu, and presented to the Shwedagon Pagoda of Dagon (today's Yangon, Myanmar).

In 1484, King Dhammazedi's astrologer advised him to postpone casting of the bell, because it was at the inauspicious time of the Crocodile constellation, and he predicted the bell would not produce any sound. After the bell was completed, it reportedly had an unpleasant tone.

According to contemporary texts, the bell was cast from 180,000 viss (294 t) of metal which included silver and gold, as well as copper and tin. It was said to be twelve cubits high and eight cubits wide. In 1583, Gasparo Balbi, an italian gem merchant, visited the Shwedagon Pagoda and described the King Dhammazedi Bell in his diary as being engraved from top to bottom with writing that he could not decipher:

"I found in a faire hall a very large bell which we measured, and found to be seven paces and three hand breadths and it is full of letters from the top to the bottom but there was no Nation that could understand them."

European explorers and merchants began to make contacts in Lower Burma in the early 16th century. Filipe de Brito e Nicote, a Portuguese warlord and mercenary known as Nga Zinka to the Burmese, arrived in Lower Burma sometime in the 1590s. At that time, Syriam (now known as Thanlyin) was the most important seaport in the Burmese Kingdom of Taungoo.

In 1599, De Brito led an Arakanese force which sacked Syriam and Pegu (now known as Bago), the capital of Lower Burma. The King of Arakan appointed him as governor of Syriam. By 1600, De Brito had extended his power across the Bago River to Dagon and the surrounding countryside. De Brito declared independence from the Arakanese king in 1603 and established Portuguese rule under Aires de Saldanha, Viceroy of Portuguese India.

In 1608, De Brito and his men removed the Dhammazedi Bell from the Shwedagon Pagoda and rolled it down Singuttara Hill to a raft on the Pazundaung Creek. From here, the bell was hauled by elephants to the Bago River. The bell and raft were lashed to his flagship for the journey across the river to Syriam to be melted down and made into cannons. The load proved too heavy, and at the confluence of the Bago and Yangon Rivers, off what is now known as Monkey Point, the raft broke up and the bell went to the bottom, taking de Brito's ship with it.

Burmese forces under King Anaukpetlun re-captured Syriam in September 1613. De Brito was executed by impalement on a wooden stake.