Peter Rainier, Jr. (1741–April 7, 1808) was a British naval leader.

Rainier was born in England, the grandson of Daniel Regnier, a Hugenot refugee, and the son of Peter Rainier of Sandwich. He enlisted in the Royal Navy in 1756 at the age of 15. He served on the HMS Oxford, Yarmouth, Norfolk, and Burford. On May 26, 1768, working for the British East India Company, Rainier was promoted to lieutenant.

During the American Revolutionary War, Rainier was severely wounded on July 8, 1778, while capturing a large American privateering ship. He was promoted in rank. In 1790, he became the commander of the HMS Monarch. On May 8, 1792, Mount Rainier in modern-day Washington was named after Rainier (then a rear admiral) by George Vancouver:

"The weather was serene and pleasant, and the country continued to exhibit between us and the eastern snowy range the same luxuriant appearance. At is northern extremity, Mount Baker bore by compass N. 22E.; the round snowy mountain, now forming its southern extremity, and which, after my friend, Rear Admiral Rainier, I distinguish by the name of Mount Rainier, bore N(S) 42 E."

In early 1793, Rainier commissioned the 74-gun Suffolk.

From 1794 to 1804, Rainier commanded Royal Navy operations in the East Indies. During his tenure, large swaths of territory came under British control.

In 1795, he was promoted to Rear-Admiral. In 1799, Rainier was promoted to the rank of vice admiral. He served in the East Indies as commodore and commander-in-chief of a fleet until 1804, when he returned to England and retired from active duty. After Rainier's retirement, he continued to be consulted by the ministry and in 1805 was promoted to Admiral of the Blue in the celebratory promotions following the British victory at the Battle of Trafalgar. In 1807, he became a member of Parliament. He died the following year at his home on Great George Street, Westminster.

1741 births | 1808 deaths | Royal Navy admirals