Mel Gibson is lining up his next three pictures, one of which now seems likely to be the much-anticipated “Lethal Weapon 4″ for Warner Bros.Gibson and his “Conspiracy Theory” filmmakers Richard Donner and Joel Silver (who are also part of the “Lethal” creative team) are close to joining hands on a fourth installment of the franchise. The first three “Lethal Weapon” films jointly grossed more than $350 million in the U.S. alone. In the scenario by writer Brian Helgeland quickly coming together for “Lethal Weapon 4,” Danny Glover will return as Gibson’s co-star, Donner will direct and Silver will produce. However, Gibson has an obligation to make a film first with Paramount Pictures. If all goes well, Gibson will star in “Parker” starting in the fall. The “Parker” script was also penned by “Conspiracy Theory” writer Helgeland, who will make his feature film helming debut on the pic (Daily Variety, June 20). Co-production possible “Parker” may end up as a co-production between Warner Bros. and Paramount, as Gibson’s Icon Prods. has a deal with both studios. When Gibson and Icon partner Bruce Davey structured their deal between Paramount and Warner Bros., Gibson agreed to both produce and star in films for each. Paramount had offered several projects to Gibson over the past month, including the actioner “Pathfinder,” which the actor passed on. “Parker,” which had been in development at Icon, focuses on a criminal who is set up by his partners in crime and then systematically goes after them to exact revenge. Sources say Gibson had been looking for a project to do this fall. The hitch is that the underlying rights to the project, the Richard Stark novel “The Hunter,” are owned by WB and controlled by Silver. The hitch would be solved by Paramount becoming a partner in the pic with WB. Gibson, whose obligation to star in a Par film would thus be met, then could agree to do “Lethal Weapon 4.” Paramount chairman Sherry Lansing must agree to accept half of “Parker” as fulfillment of Gibson’s obligation to the studio. If Paramount says no to the deal, Gibson then would do “Parker” for WB exclusively, with “Lethal Weapon” going by the wayside. On the other hand, Gibson could argue that he acted in good faith with Paramount, so a no from Par on the “Parker” arrangement could mean the studio ends up with nothing from Gibson for a long time. $20 million upfront fee Gibson is expected to get his $20 million upfront fee for “Lethal Weapon.” Gibson’s backend participation is such that — depending on the success of the film — he could garner an extra $15 million to $20 million in total compensation. Warner Bros. denies that a deal on “Lethal” is close, and especially the projected precedent-setting compensation package. That could be because there is no script yet. However, if Helgeland turns in a killer “Lethal” script, the film could be in production as early as January 1998. The last one bowed in 1992. ‘Fahrenheit 451′ After “Lethal Weapon,” Gibson may finally get behind the camera for “Fahrenheit 451,” which would be his first directing/starring project since winning the best director Oscar for “Braveheart.” “Fahrenheit” is being co-produced by Icon and Storyline Entertainment. After numerous drafts, sources say Gibson’s close to getting the script he wants to shoot. He’s been working with Terry Hayes, who, with director George Miller, scripted the last two films in the “Mad Max” franchise, which elevated Gibson to international stardom. Gibson is repped by ICM’s Ed Limato.