The Hoops had the chance to win the game but Samaras missed a penalty nine minutes from the end.
Steven Davis was ruled to have fouled Anthony Stokes, but McGregor pushed Georgios Samaras’s late spot-kick wide.
All the controversy surrounding death threats to Neil Lennon had led to a tense build up.
Celtic fans travelled to Ibrox with a huge banner which showed a picture of Lennon with the words ‘Celtic to the Core’ emblazoned on it.
The first half was tense – but frantic football failed to produce many clear cut chances.
Rangers’ Kyle Lafferty headed wide just after the break, while McGregor also thwarted Daniel Majstorovic when it looked like Celtic were about to take the lead.
And the Scotland goalkeeper’s penalty save prevented Celtic securing a victory that would have sent them to the top of the Scottish Premier League by two points with a game in hand.
The build-up to the game had been overshadowed by parcel bombs sent to Celtic manager Neil Lennon and two other prominent fans.
Walter Smith went into his final Old Firm game as Rangers manager hoping to even up the scores with Celtic having won three and lost two of the previous Glasgow derbies this season.
But an even game that ended both sides’ five-match winning run concluded with Lennon the happier of the managers as his side will now win the title if they win all five of their remaining fixtures.
The first controversy came after 22 minutes when Samaras and David Weir were both given a yellow card for shoving.
Scott Brown had Celtic’s first effort on goal with a low drive from 20 yards that curled a few yards wide after Mark Wilson dispossessed Davis.
Steven Naismith wildly sliced wide from 12 yards at the other end when found in the clear at the far post by a long Sasa Papac diagonal ball as the first half deteriorated into a midfield war of attrition.
Weir had the first chance of the second half but headed over from 14 yards after climbing well to meet a Davis corner, while Daniel Majstorovic did well to deflect a Naismith drive wide.
Kyle Lafferty squandered a great chance to give Rangers the lead when he beat Mulgrew to a Wylde cross to the front post, but the forward flashed his header just wide.
Celtic responded and a 22-yard Beram Kayal drive flew inches wide then McGregor produced a breathtaking finger-tip save to deflect a close-range Majstorovic header for a corner.
Lafferty flashed a free-kick wide of the far post, while Naismith fired across the face of goal and narrowly past from the edge of the box.
McGregor did well to tip an Emilio Izaguirre chip over the crossbar after the full-back had stepped inside Whittaker.
It looked like Celtic would secure the victory when Thomson pointed to the spot after 83 minutes.
Davis obstructed Stokes – but Samaras saw his penalty saved by Mcgregor.
Stokes went down again in the box in the dying seconds under a John Fleck challenge, but this time Thomson booked the substitute for diving.Tags: