Francis Joseph Julian "Muggsy" Spanier (November 9, 1901 – February 12, 1967) was a prominent cornet player based in Chicago. He was renowned as the best trumpet/cornet in Chicago until Bix Beiderbecke entered the scene.

Muggsy led several traditional/"hot" jazz bands, most notably Muggsy Spanier and His Ragtime Band (which did not, in fact, play ragtime but, rather, "hot jazz" that would now be called Dixieland). This band set the style for all later attempts to play traditional jazz with a swing rhythm section. Its key members, apart from Muggsy, were: George Brunies - later Brunis - (trombone and vocals), Rod Cless (clarinet), George Zack or Joe Bushkin (piano), Ray McKinstry, Nick Ciazza or Bernie Billings (tenor sax), and Bob Casey (bass). A number of competent but unmemorable drummers worked in the band. In the early 1920s, Spanier played with the Bucktown Five in Chicago.