Smash! was a weekly British comic book, published initially by Odhams Press and subsequently by IPC Magazines, from 5 February 1966 to 3 April 1971. After 257 issues it merged into Valiant.

During 1967 and 1968 Smash! was part of Odhams' Power Comics line, notable for its publication of American superhero strips. During this period, alongside British humour strips, Smash! included black-and-white superhero reprints originally published in the US by Marvel Comics and DC Comics. In late 1968, Smash! absorbed its sister titles Pow! and Fantastic, thereby becoming the last surviving Power Comics title. In March 1969 Smash! underwent a major relaunch, and thereafter featured solely British content: a mixture of humour, sporting and adventure strips. A further relaunch in 1970 was almost as extensive, with a number of new strips introduced and an equal number cancelled.

Smash! was sized 9.75" × 12" (#1–162) and 9.25" × 12" (#163–257), and had a four-colour cover and black-and-white interior.

Smash! was owned by the International Publishing Corporation (IPC), a company formed in 1963 – through a series of corporate mergers – by Cecil Harmsworth King, chairman of the Daily Mirror and the Sunday Pictorial (now the Sunday Mirror). All the comics owned by it were published by one or other of the subsidiary companies brought together to form IPC, including Fleetway Publications and Odhams Press.

Odhams' comics line was produced in London from 64 Long Acre, overseen by managing editor Alfred Wallace. Following the initial success of the anarchic humour comic Wham! in 1964, Smash! was launched (with a cover price of 7d for 24 pages) on 5 February 1966 following a similar model. Early on, Smash! successfully integrated superhero strips — Marvel Comics' the Hulk and DC Comics' Batman — into its lineup, prompting Wham! to do the same (with the Fantastic Four) shortly thereafter.

Odhams branded the two titles, and three more launched in quick succession — all heavily featuring Marvel reprints — as part of the Power Comics line, a gimmick dreamed up by Odhams to unify their five titles under a common banner (Smash! became a Power Comic with issue #44, published 3 December 1966). The Power Comics line was published under a three-man editorial team known as Alf, Bart, and Cos. "Alf" (Alfred Wallace) was the managing editor, and "Cos" (Albert Cosser) was the editor directly responsible for Smash!

Odhams comics titles faced their first serious crisis in May 1967. The editorial page warned readers in issue #68 (20 May 1967) that Smash!, initially printed by St. Clements Press Ltd of London, had to find new printers within one month, or face closure. As it turned out, Odhams were able to sign a contract with Southernprint Ltd of Poole in Dorset in time to maintain publication.

On 14 September 1968, with issue 137, the title merged with Pow! (which had previously absorbed Wham), becoming Smash! and Pow!. Later on 2 November, with issue 144, it merged with Fantastic (which had previously absorbed Terrific), becoming Smash and Pow incorporating Fantastic.