The January transfer window is fast approaching and Vladimir Ivic may be keen to make some tweaks to his squad as he takes aim at promotion to the Premier League. 

Watford have got a squad that is likely to be the envy of many in the Championship but he may still fancy adding one or two more players.

The Hornets have made some smart signings in the past and with that in mind, we've outlined six of the best bargain free transfers...

Most of the centre-back's Watford appearances came in Mariappa's first spell at the club but he certainly proved valuable after rejoining on a free transfer from Crystal Palace.

The ever-reliable defender was a regular in the first team as the Hornets battled in the Premier League in the late 2010s and proved a real bargain.

Another central defender that was brought in at low cost and proved a fantastic signing, Cathcart arrived on a free transfer from Blackpool in 2014 and has gone on to make nearly 200 appearances – including helping them secure promotion back in 2014/15.

The 31-year-old is continuing to show his worth and after signing a new long-term deal last year has made 15 appearances this term.

The midfielder joined from Wigan on a free transfer in 2015 and proved his worth straight away, helping Watford secure promotion to the Premier League that season.

His efforts as they extended their stay in the top flight the following season shouldn't be forgotten either.

The powerful striker arrived from League One Carlisle United on a free transfer in 2009 and made a fast start for Watford in the Championship.

Graham scored 41 goals over two seasons with the Hornets before they cashed in and sold him to Swansea City.

The American centre-back was a fantastic servant to the club, making more than 200 appearances at the heart of their defence.

DeMerit arrived at Vicarage Road on a free transfer from Northwood FC in 2010, a move that was clearly an absolute bargain.

The tricky forward has become a household name in the EFL but it was the Hornets that first brought him to England, signing him on a free transfer from Udinese.

It would prove a sensational acquisition as he went on to score 21 goals and provide 23 assists over three seasons, helping them to get promoted in the process.