Jonathan Mark Ansell (born 10 March 1982) is an English singer, formerly the high tenor of the vocal group G4.Whilst he was at the Guildhall School of Music and Drama he formed the pop-opera boyband G4 with Mike Christie, Tom Lowe, and Ben Thapa, three other Guildhall students.

Later, due to artistic differences, Tom Lowe resigned as bass, and Matthew Stiff took his place. Their name, G4, comes from the fact that they were all students at the Guildhall School of Music and Drama and stands for Guildhall 4.

G4 were discovered after finishing second on ITV talent show The X Factor in 2004. G4's self-titled debut album produced by the legendary Trevor Horn and Brian Rawling, reached Number One for Mother's Day weekend 2005 and sold over 245,000 copies in the first week.

In total they released 3 albums, sold in excess of 1.5 million albums in the UK, completed 5 sell-out UK tours, sold in excess of 40,000 Live at the Royal Albert Hall DVDs (one of the concerts on their first tour) and also released a best selling autobiography Our Way.

On 5 April 2007, G4 announced on GMTV that they were calling it a day at the end of July 2007.Jonathan signed with new management Jonathan Shalit in 2007 and secured a £1 million, 5 album deal with Universal Classics and Jazz (UCJ) which is part of the Universal Music Group.

He was offered an album deal by the three major labels, EMI, Sony and Universal." His first solo album with UCJ, Tenor at the Movies, was released on 18 February 2008.For 5 Sunday afternoons from 17th February 2008 Jonathan Ansell presented The Great Movie Composers on ClassicFM coinciding with the release of his solo album.

On 24th February 2008 Jonathan's album Tenor at the Movies went straight to number 1 in the Classical Chart and stayed there for 3 weeks and reached Number 9 in mainstream charts making him the youngest tenor ever to top the Classical Charts.