Pensions received by Canadian residents from the United Kingdom are required to report the full amount of the pension income for tax purposes. The pension is eligible for the $2,000 pension credit however.
Canadian residents receiving U.S. social security are only required to pay tax on 85% of the pension received unless they have been receiving the pension continuously since January 1, 1996 for which the income is only 50% taxable. The net amount is also eligible for the $2,000 pension credit.
German pensions received by Canadian residents are somewhat more complex. The amount taxable is dependent upon the age you were when you started receiving the pension.
Canadian residents receiving a pension from Italy for military service are subject to tax depending upon the worldwide income.
Please see CRA's information page for more details on foreign pensions.