Big Tom and The Mainliners were a Country and Irish showband from the Castleblayney area of County Monaghan, Ireland.

Originally named the "Mainliners Showband", sometimes prefixed with the word Mighty, and already beginning to make a name on the country music scene in Ireland and Scotland, particularly since mid 1965 when the late John McCormack of Rockcorry became their manager, the band received its biggest break and widespread fame appearing on RTÉ Television's Showband Show broadcast on Saturday, 21 May, 1966. In Big Tom McBride's own words, published in the Connaught Telegraph on 27 June, 1984, their appearance on it was "made possible by the herculean efforts of Tommy Toal" aka Fat Sam, late and much-lamented radio presenter, singer, entertainer, and a pioneer of Local and Community Radio in Ireland with Radio Monaghan, Big M and Hometown Radio in his native town of Castleblayney. On the Showband Show, Tom sang Gentle Mother and such was the huge positive public response and demand for more, it was soon recorded and reached number 7 in the Irish charts. Eventually, in line with other Irish Showbands where a single man was used to take centre stage, the name "Big Tom and the Mainliners" was adopted and became synonymous with 'The best in country and Irish music' and Big Tom became the undisputed King of Country Music.

• "Big" Tom McBride – lead vocals, saxophone, rhythm guitar
• Seamus McMahon – lead guitar, fiddle, vocals
• Henry McMahon – tenor sax, vocals, bandleader, percussion
• John Beattie – keyboards, piano
• Cyril McKevitt – trombone, vocals
• Ronnie Duffy – drums, vocals
• Ginger Morgan – Bass guitar, vocals

In May 1975, lead vocalist Tom McBride (known as "Big Tom") left the band and formed a new band "Big Tom and the Travellers" under the management of Top Rank Entertainment (owned by country music tycoon Tony Loughman). The band subsequently used other lead vocalists, including John Glenn, Tom Allen and Jan Lynch, and occasionally performed without a front man. Big Tom would rejoin the band in 1989 and they continued to play and record regularly until 1998.

Due to their advancing years the band have only had occasional 'comeback' tours. They have toured more regularly in the last 4 years with the original band playing together.

In 2004, Big Tom’s son Dermot McBride took Ginger Morgan's place on Bass Guitar, Peter McCarthy took Ronnie Duffy's place on drums and Robert Browne, a second keyboardist in the band, appeared to take Cyril McKevitt's place on Trombone (however both were performing for the band in their Q4 2005 tour). In 2005, the band recorded a hit single The Same Way You Came In. In November 2006, McBride suffered a sudden heart attack, jeopardising plans for future tours, however doctors later gave the all clear for him to have a mini tour of Ireland in February, 2008.^[1] It is believed that the band will revert to the seven original Mainliners for this tour.^[2] Cyril McKevitt died of a heart attack, on Tuesday 15 September 2009, just days after the end of the band's Summer 2009 tour. Martin Campbell filled McKevitt's position one year later. Since 2014 the band continue to tour on a regular basis including 8 dates in 2015–16.^[3][4]

Big Tom died on 17 April 2018.

• Big Tom – lead vocals, rhythm guitar
• Seamus McMahon – lead guitar, rhythm guitar, fiddle, vocals
• Henry McMahon – bandleader, tenor sax, vocals, percussion
• John Beattie – keyboards, piano
• Martin Campbell – trombone, vocals
• Ronnie Duffy – drums, vocals
• Ginger Morgan – bass guitar, vocals
• Harry Conlon – Organ