The Grand Order of Water Rats is a British entertainment industry fraternity and charitable organisation based in London.

Founded in 1889 by the music hall comedians Joe Elvin and Jack Lotto, the order is known for its high-profile membership and benevolent works (primarily within the performing industries).

[1] Its sister organisation is The Grand Order of Lady Ratlings, which includes female performers and family members.

In 1889, two British music hall performers, Joe Elvin, and Jack Lotto, owned a trotting pony called "Magpie".

[3] One day, as Elvin was driving the pony back to its stables in the pouring rain, a passing bus driver called out, "Wot yer got there, mate?"

Magician David Nixon wore his while appearing on television, explaining that as current King Rat, he could be fined by any other member who saw him on screen without it.

There is also a small number of Companion Rats, distinguished men from various fields of business and influence who are not performers but who have achieved recognition for their support and friendship of the Order.