First 6 Legendre Polynomials Plotted on Unit Sphere

For pretty colors :

g[ℓ_]:=SphericalPlot3D[1,θ,ϕ,Lighting->None,Axes->None,ViewPoint->{0,-50,0},Boxed->False,ColorFunctionScaling->False,ColorFunction->Function[{x,y,z,θ,ϕ,r},Glow[ColorData["ThermometerColors"][(LegendreP[ℓ,Cos[θ]]+1)/2]]
]
]

ColorData["ThermometerColors"]

GraphicsGrid[{{g[0],g[1]},{g[2],g[3]},{g[4],g[5]}}]

For gray-scale, you don't need the ColorData function

gg[ℓ_]:=SphericalPlot3D[1,{θ,0,Pi},{ϕ,0,2Pi},Lighting->None,Axes->None,ViewPoint->{0,-50,0},Boxed->False,ColorFunctionScaling->False,ColorFunction->Function[{x,y,z,θ,ϕ,r},Glow[GrayLevel[(LegendreP[ℓ,Cos[θ]]+1)/2]]
]
]

GraphicsGrid[{{gg[0],gg[1]},{gg[2],gg[3]},{gg[4],gg[5]}}]