Henson, 29, missed the momentous World Cup campaign after a wrist injury gave him little chance of proving his credentials to Warren Gatland.
The Cardiff Blues centre suffered the injury in the World Cup warm-up match against England in August and has played only three games for the Welsh region since joining in October.
But despite his lack of action, Henson is rated highly by the Wales coaching team and his ability to cover at fly-half, centre and full-back makes him a valuable commodity.
A knee injury to influential centre Jamie Roberts could open the door for Henson, who turns 30 next month.
There are six uncapped players in the group, the most surprising selection being 18-year-old Blues winger Harry Robinson.
The others were in-form Ospreys centre Ashley Beck and scrum-half Rhys Webb and the Scarlets trio of prop Rhodri Jones, lock Lou Reed and full-back Liam Williams.
Gatland has also included six men plying their trade outside Wales - France-based trio James Hook, Mike Phillips and Lee Byrne were all selected, as were Exeter prop Craig Mitchell, Saracens prop Rhys Gill and Sale back-rower Andy Powell.
That sextet of players will not attend all of Wales' pre-tournament training camp in Spala, Poland, but will be present for three days - the maximum stipulated by International Rugby Board regulations as they are not obliged to be released by their clubs for the full seven-day camp.
Gatland has been robbed of his first-choice second-row pairing through injury with Alun Wyn Jones and Luke Charteris missing out while Scarlets back-rowers Josh Turnbull and Rob McCusker are also ruled out along with Newport Gwent Dragons hooker Lloyd Burns.
And there is no place for veteran fly-half Stephen Jones, whose international career appears to be at an end following a record 104 caps.
Gatland said: "We have had to strike a balance with this squad. The majority are those players who excelled for Wales during the Rugby World Cup, but we are also taking the opportunity to look at one or two youngsters before probably cutting our numbers even further before the start of the Six Nations.
"We have kept a couple of older heads and we have injuries, with Alun Wyn Jones, Josh Turnbull, Rob McCusker and Luke Charteris all unavailable to us, but the emphasis on development and planning for the future is there for everyone to see.
"These are exciting times for Welsh rugby. We showed a huge amount of potential at the Rugby World Cup in New Zealand and we'll be working as hard as humanly possible to ensure we reach our potential in this year's Six Nations Championship."
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