For landscapes, the 18-55mm kit lens is a reasonable starter.
If you want to go wider, there is the sigma 10-20mm, sigma 8-16mm, tokina 11-16mm and the canon 10-22mm, ultra-wide angles that'll let you capture huge landscapes. Or there is the tamron 17-50 f/2.8, which isn't really any wider than the kit lens but will be sharper (the non VC version at least).
For wildlife, things can get very expensive.
For a starter lens, something like the canon 55-250mm or nikon 55-200mm are good bets, with the more expensive canon 70-300IS or nikkor 70-300VR being the next step up. But you'll have to get very close to take wildlife shots with lenses like this.
If you go into more serious set ups, there is the sigma 120-400 OS and 150-500 OS, two of the best budget wildlife lenses available.
Above that there is the sigma 50-500 OS, canon 100-400L IS, canon 400mm f/5.6L, canon 300 f/4L IS, nikkor 300mm f/4 and the nikkor 80-400VR.
Even with the big telephotos, you still need to be close to the subject. It's a good idea to spend some time with shorter lenses, as they force you to spend time learning good field-craft and getting close to your subjects, skills that are essential for a good wildlife photographer.