From Fabregas's corner, Gallas stole in completely unmarked at the far post to volley in and hand Arsenal a lifeline they had barely deserved.
Charlton were incensed with 20 minutes to go as Lisbie's overhead kick struck Gallas' outstretched arm, but referee Mark Clattenburg was unmoved.
Down to 10 men, Arsenal needed to hit back quickly and almost snatched an equaliser when Toure's shot deflected off Gallas and skidded narrowly wide.
During the draw at St Andrew's in February, Gallas, 30, kicked an advertising hoarding and stood in the other half of the pitch as James McFadden scored a last-minute penalty.
Gallas, 32, and fellow centre-backs Sol Campbell and Mikael Silvestre are all out of contract in June and Gunners chairman Peter Hill-Wood described Gallas's demands for a new contract as "quite extravagant".
The Gunners were rocked when Matthieu Flamini hesitated on the edge of the box, the ball found its way to Taylor and his side-foot shot arrowed into the corner via Gallas's ankle.
Arsenal's second owed much to Gallas, who rode a succession of tackles, before touching the ball to Henry.
Of Arsenal's other attempts, William Gallas shot over from 10 yards and Eduardo screwed an effort wildly off target - however, that was still more then Bolton managed in the opening 45 minutes.
The two dropped points reduced Arsenal's then lead at the Premier League summit to two points and many believed Gallas' actions undermined Arsenal's title challenge.
The keeper's ill-judged dash from goal allowed Pato to round him, and as he struggled to regain his ground Gomes was relieved to see Gallas clear Robinho's deflected shot off the line.
Taylor's deflected drive doubled the lead before William Gallas volleyed home to cut the deficit.
"We just have to believe in ourselves, " Gallas, 33, told the club's website.
He had two good shooting opportunities in the first half but from the first he shot wide of the far post from 25 yards, and then saw a close-range effort blocked by France keeper Lloris after William Gallas had inexplicably backed away from Salcido's run.
Arsenal grabbed a controversial equalizer in the 52nd minute when Cesc Fabregas latched on to Andrey Arshavin's pass to slip the ball through Jaaskelainen's legs but there had appeared to be an earlier foul when William Gallas appeared to catch Mark Davies on the ankle.
Redknapp has already bolstered his defence with the signing of William Gallas and the club are reportedly in talks with Real Madrid's holding midfielder Lassana Diarra.
And Fulham's Brede Hangeland and Senegal defender Pape Diakhate are thought to be on Wenger's radar as he looks to shore up his shaky rearguard, although William Gallas could be on his way out of the club.
Wenger demonstrated his frustration in the final seconds of the match when his side were denied a late equaliser when William Gallas was adjudged offside in the build up to Robin Van Persie's side-foot finish.
France international Gallas, who won two Premier League titles and a League Cup winner's medal with Chelsea before moving to Arsenal, first trained with his new team-mates on Monday after agreeing terms on Saturday on a one-year deal with an option to extend.
Koscielny improves Wenger's defensive options as Sol Campbell is mulling over a new one-year deal and William Gallas and Mikael Silvestre likely to leave.
Goalkeeper Heurelho Gomes saved from Zlatan Ibrahimovic and Pato, while William Gallas kept Milan at bay with a priceless goal-line clearance from Robinho's deflected shot.
Song had filled in for Gallas in central defense against Barcelona, but was caught out for both of Ibrahimovic's goals.
Brazilian midfielder Denilson fired Arsenal's opener from the edge of the penalty box before headers from new defender Thomas Vermaelen and William Gallas stunned the home side, who had been hoping to break into the top-four this season after finishing fifth in 2008-09.
Arsenal pulled a goal back with 18 minutes left, Gallas turning home from almost on the line after Kolo Toure touched on substitute Tomas Rosicky's corner.
Redknapp admitted that the acquisition of Gallas may not mark the end of his summer spending, with Brazilian Sandro being Tottenham's only other capture of this transfer window.
BBC: Tottenham sign defender William Gallas on one-year deal
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