You mean players playing in their first playoff game?
In that case, here's a list of every skater who played in minimum 1 NHL game this season, whose team qualified for the playoffs and who, as individuals, have never played in the playoffs:
John Klingberg (DAL), Mattias Janmark (DAL), Radek Faksa (DAL), Stephen Johns (DAL), Jamie Oleksiak (DAL), Jason Dickinson (DAL), Brett Ritchie (DAL), Devin Shore (DAL), Curtis McKenzie (DAL), Esa Lindell (DAL), Mike Reilly (MIN), Christian Folin (MIN), Zac Dalpe (MIN), Gustav Olofsson (MIN), Tyler Graovac (MIN), Kurtis Gabriel (MIN), Brett Bulmer (MIN), Christoph Bertschy (MIN), Robby Fabbri (STL), Colton Parayko (STL), Magnus Paajarvi (STL), Joel Edmundson (STL), Ty Rattie (STL), Jeremy Welsh (STL), Petteri Lindbohm (STL), Artemi Panarin (CHI), Erik Gustafsson (CHI), Dennis Rasmussen (CHI), Brandon Mashinter (CHI), Viktor Svedberg (CHI), Tanner Kero (CHI), Ryan Hartman (CHI), Mark McNeill (CHI), Kyle Baun (CHI), Vince Hinostroza (CHI), Josh Manson (ANA), Shea Theodore (ANA), Brandon Pirri (ANA), Nick Ritchie (ANA), Korbinian Holzer (ANA), Harry Zolnierczyk (ANA), Michael Sgarbossa (ANA), Stefan Noesen (ANA), Viktor Arvidsson (NAS), Miikka Salomaki (NAS), Austin Watson (NAS), Colton Sissons (NAS), Anthony Bitetto (NAS), Petter Granberg (NAS), Stefan Elliott (NAS), Brayden McNabb (LAK), Andy Andreoff (LAK), Nick Shore (LAK), Jamie McBain (LAK), Michael Mersch (LAK), Derek Forbort (LAK), Kevin Gravel (LAK), Nic Dowd (LAK), Joonas Donskoi (SJS), Chris Tierney (SJS), Melker Karlsson (SJS), Dylan DeMelo (SJS), Matt Tennyson (SJS), Barclay Goodrow (SJS), Nikolay Goldobin (SJS), Ryan Carpenter (SJS), John McCarthy (SJS), Bryan Lerg (SJS), Mirco Mueller (SJS), Aleksander Barkov (FLA), Jonathan Huberdeau (FLA), Vincent Trocheck (FLA), Aaron Ekblad (FLA), Nick Bjugstad (FLA), Alex Petrovic (FLA), Quinton Howden (FLA), Logan Shaw (FLA), Corban Knight (FLA), Rocco Grimaldi (FLA), Connor Brickley (FLA), Steven Kampfer (FLA), Greg McKegg (FLA), Michael Matheson (FLA), John Mcfarland (FLA), Brent Regner (FLA), Kyle Rau (FLA), Garrett Wilson (FLA), Shane Prince (NYI), Ryan Pulock (NYI), Adam Pelech (NYI), Alan Quine (NYI), Ross Johnston (NYI), Mike Angelidis (TBL), Yanni Gourde (TBL), Joel Vermin (TBL), Slater Koekkoek (TBL), Tye McGinn (TBL), Matt Taormina (TBL), Luke Witkowski (TBL), Dylan Larkin (DET), Andreas Athanasiou (DET), Teemu Pulkkinen (DET), Anthony Mantha (DET), Tomas Nosek (DET), Dmitri Orlov (WAS), Nate Schmidt (WAS), Stanislav Galiev (WAS), Aaron Ness (WAS), Zack Sill (WAS), Ryan Stanton (WAS), Sean Collins (WAS), Chandler Stephenson (WAS), Shayne Gostisbehere (PHI), Scott Laughton (PHI), Sam Gagner (PHI), Pierre-Edouard Bellemare (PHI), Chris VandeVelde (PHI), Evgeny Medvedev (PHI), Nick Cousins (PHI), Brandon Manning (PHI), Jordan Weal (PHI), Taylor Leier (PHI), Tom Kuhnhackl (PIT), Bryan Rust (PIT), Conor Sheary (PIT), Justin Schultz (PIT), Derrick Pouliot (PIT), Oskar Sundqvist (PIT), Daniel Sprong (PIT), Dominik Simon (PIT), Josh Archibald (PIT), Kael Mouillierat (PIT), Scott Wilson (PIT), Oscar Lindberg (NYR), Dylan McIlrath (NYR), Marek Hrivik (NYR), Chris Summers (NYR), Brady Skjei (NYR)
Now this is a very generous list that includes players that have no yet been called up yet and/or will be integral parts of their AHL team's playoffs runs, and also exclusive in that it does not take into account any potential players that did not play a regular season game, but may be recalled after their AHL or CHL team is finished.
If OP meant players who are making their
NHL debuts by playing in a playoff game, ala Chris Kreider a couple of years back, I cannot think of any right now... I think all the college signings for
this year already played in a regular season game, and the rest don't have contracts until
next year, and again, I'm sure there are players in the AHL or CHL who may be recalled, and haven't made their NHL debut, I just cannot speak to any of them or these teams.